Poltergeists

Poltergeists are ghosts that make noises or move objects through the air. Some scientists and skeptics propose that all poltergeist activity that they can't trace to fraud has a physical explanation such as static electricity, electromagnetic fields, ultra-, and infrasound and/or ionized air. In some cases, such as the Rosenheim poltergeist case, the physicist F. Karger from the Max-Planck-Institut für Plasmaphysik and G. Zicha from the Technical University of Munich found none of these effects present and psi proponents claim that no evidence of fraud was ever found, even after a sustained investigation from the police force and CID, though criminologist Herbert Schäfer quotes an unnamed detective watching the agent pushing a lamp when she thought nobody was looking. However, whether this is true or not, police officers did sign statements that they had witnessed the phenomena. Other aspects of the case were hard to explain: The time service was rung hundreds of times, with a frequency impossible with the mechanical dialing phones of 1967. The municipal authority disconnected the office from the mains supply and hooked it up to a dedicated generator hoping to stabilize the current. But surges in current and voltage still occurred with no detectable cause according to Zicha and Karger. Others think poltergeist phenomena could be caused by more mundane phenomena, such as unusual air currents, air vibrations such as in acoustic levitation, or tremors caused by underground streams.^{[Citation Needed]}

John Hutchinson has claimed that he has created poltergeist effects in his laboratory. Also worth noting is that scientist David Turner proposes that poltergeists and ball lightning may be linked phenomena. Some scientists go as far as calling them pseudo-psychic phenomena and claim that under some circumstances they are caused by obscure physical effects. Parapsychologists William G. Roll and Dean Radin, physicist Hal Puthoff and head of electrical engineering at Duke University who specializes in electromagnetic field phenomena, claim that poltergeist phenomena [the movement of objects at least] could be caused by anomalies in the zero-point field, this is outlined in the above article and in Roll's book Unleashed and mention is made of it in a chapter of Dean Radin's book Entangled Minds. The basic theory is that poltergeist movements are repulsive versions of the casimir effect that can put pressures on objects. Thus, anomalies in this field could conceivably move objects. This theory has also been mentioned in the current book on paranormal phenomena Science by Marie D. Jones.

The theory is not complete, however, because it accounts for the movement of objects but not for the strange voices, seeming personality, and strange electrical effects displayed in some cases.

Past Continuous: [was/were + present participle]

Examples:You were studying when she called./ Were you studying when she called?/ You were not studying when she called.

USE 1 Interrupted Action in the Past

Use the Past Continuous to indicate that a longer action in the past was interrupted. The interruption is usually a shorter action in the Simple Past. 626e412g Remember this can be a real interruption or just an interruption in time.

Examples: I was watching TV when she called./ When the phone rang, she was writing a letter./ While we were having the picnic, it started to rain./ What were you doing when the earthquake started? / I was listening to my iPod, so I didn't hear the fire alarm. / You were not listening to me when I told you to turn the oven off./ While John was sleeping last night, someone stole his car./ Sammy was waiting for us when we got off the plane. / While I was writing the email, the computer suddenly went off./ A: What were you doing when you broke your leg?/ B: I was snowboarding.

USE 2 Specific Time as an Interruption

In USE 1, described above, the Past Continuous is interrupted by a shorter action in the Simple Past. 626e412g However, you can also use a specific time as an interruption.

Examples: Last night at 6 PM, I was eating dinner./ At midnight, we were still driving through the desert./ Yesterday at this time, I was sitting at my desk at work.

IMPORTANT

In the Simple Past, a specific time is used to show when an action began or finished. In the Past Continuous, a specific time only interrupts the action.

Examples: Last night at 6 PM, I ate dinner./ I started eating at 6 PM./ Last night at 6 PM, I was eating dinner. I started earlier; and at 6 PM, I was in the process of eating dinner

USE 3 Parallel Actions

When you use the Past Continuous with two actions in the same sentence, it expresses the idea that both actions were happening at the same time. The actions are parallel.

Examples: I was studying while he was making dinner./ While Ellen was reading, Tim was watching television./ Were you listening while he was talking? / I wasn't paying attention while I was writing the letter, so I made several mistakes. / What were you doing while you were waiting? / Thomas wasn't working, and I wasn't working either. / They were eating dinner, discussing their plans, and having a good time.

USE 4 Atmosphere

In English, we often use a series of parallel actions to describe the atmosphere at a particular time in the past.

Example:When I walked into the office, several people were busily typing, some were talking on the phones, the boss was yelling directions, and customers were waiting to be helped. One customer was yelling at a secretary and waving his hands. Others were complaining to each other about the bad service.

USE 5 Repetition and Irritation with "Always"

The Past Continuous with words such as "always" or "constantly" expresses the idea that something irritating or shocking often happened in the past. The concept is very similar to the expression "used to" but with negative emotion. Remember to put the words "always" or "constantly" between "be" and "verb+ing."

Examples: She was always coming to class late./ He was constantly talking. He annoyed everyone./ I didn't like them because they were always complaining.

While vs. When

Clauses are groups of words which have meaning, but are often not complete sentences. Some clauses begin with the word "when" such as "when she called" or "when it bit me." Other clauses begin with "while" such as "while she was sleeping" and "while he was surfing." When you talk about things in the past, "when" is most often followed by the verb tense Simple Past, whereas "while" is usually followed by Past Continuous. "While" expresses the idea of "during that time." Study the examples below. They have similar meanings, but they emphasize different parts of the sentence.

Examples: I was studying when she called./ While I was studying, she called.

REMEMBER Non-Continuous Verbs / Mixed Verbs

It is important to remember that Non-Continuous Verbs cannot be used in any continuous tenses. Also, certain non-continuous meanings for Mixed Verbs cannot be used in continuous tenses. Instead of using Past Continuous with these verbs, you must use Simple Past.

Examples: Jane was being at my house when you arrived. Not Correct/ Jane was at my house when you arrived. Correct

ADVERB PLACEMENT

The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.

Examples: You were just studying when she called./ Were you just studying when she called?

ACTIVE / PASSIVE

Examples:

• The salesman was helping the customer when the thief came into the store. Active
• The customer was being helped by the salesman when the thief came into the store. Passive

Simple Past: [VERB+ed] or irregular verbs

Examples: You called Debbie./ Did you call Debbie?/ You did not call Debbie.

Complete List of Simple Past Forms

USE 1 Completed Action in the Past

Use the Simple Past to express the idea that an action started and finished at a specific time in the past. Sometimes, the speaker may not actually mention the specific time, but they do have one specific time in mind.

Examples: I saw a movie yesterday./ I didn't see a play yesterday./ Last year, I traveled to Japan./ Last year, I didn't travel to Korea./ Did you have dinner last night? / She washed her car./ He didn't wash his car.

USE 2 A Series of Completed Actions

We use the Simple Past to list a series of completed actions in the past. These actions happen 1st, 2nd, 3rd, 4th, and so on.

Examples: I finished work, walked to the beach, and found a nice place to swim./ He arrived from the airport at 8:00, checked into the hotel at 9:00, and met the others at 10:00./ Did you add flour, pour in the milk, and then add the eggs?

USE 3 Duration in Past

The Simple Past can be used with a duration which starts and stops in the past. A duration is a longer action often indicated by expressions such as: for two years, for five minutes, all day, all year, etc.

Examples: I lived in Brazil for two years./ Shauna studied Japanese for five years./ They sat at the beach all day./ They did not stay at the party the entire time. / We talked on the phone for thirty minutes./ A: How long did you wait for them?/ B: We waited for one hour.

USE 4 Habits in the Past

The Simple Past can also be used to describe a habit which stopped in the past. It can have the same meaning as "used to." To make it clear that we are talking about a habit, we often add expressions such as: always, often, usually, never, when I was a child, when I was younger, etc.

Examples: I studied French when I was a child./ He played the violin./ He didn't play the piano. / Did you play a musical instrument when you were a kid? / She worked at the movie theater after school./ They never went to school, they always skipped class.

USE 5 Past Facts or Generalizations

The Simple Past can also be used to describe past facts or generalizations which are no longer true. As in USE 4 above, this use of the Simple Past is quite similar to the expression "used to."

Examples: She was shy as a child, but now she is very outgoing/ He didn't like tomatoes before. / Did you live in Texas when you were a kid/ People paid much more to make cell phone calls in the past.

IMPORTANT When-Clauses Happen First

Clauses are groups of words which have meaning but are often not complete sentences. Some clauses begin with the word "when" such as "when I dropped my pen..." or "when class began..." These clauses are called when-clauses, and they are very important. The examples below contain when-clauses.

Examples: When I paid her one dollar, she answered my question./ She answered my question when I paid her one dollar.

When-clauses are important because they always happen first when both clauses are in the Simple Past. 626e412g Both of the examples above mean the same thing: first, I paid her one dollar, and then, she answered my question. It is not important whether "when I paid her one dollar" is at the beginning of the sentence or at the end of the sentence. However, the example below has a different meaning. First, she answered my question, and then, I paid her one dollar.

Example: I paid her one dollar when she answered my question.

ADVERB PLACEMENT

The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.

Examples: You just called Debbie./ Did you just call Debbie?

ACTIVE / PASSIVE

Examples:

• Tom repaired the car. Active
• The car was repaired by Tom. Passive

Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 metres (4 ft) and 40 kilograms (88 lb) (Maui's Dolphin), up to 9.5 m (30 ft) and ten tonnes (the Orca or Killer Whale). They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating fish and squid. The family Delphinidae is the largest in the Cetacea, and relatively recent: dolphins evolved about ten million years ago, during the Miocene. Dolphins are considered to be amongst the most intelligent of animals and their often friendly appearance and seemingly playful attitude have made them popular in human culture.

Senses

Most dolphins have acute eyesight, both in and out of the water, and their sense of hearing is superior to that of humans. Though they have a small ear opening on each side of their head, it is believed that hearing underwater is also if not exclusively done with the lower jaw which conducts the sound vibrations to the middle ear via a fat-filled cavity in the lower jaw bone. Hearing is also used for echolocation, which seems to be an ability all dolphins have. It is believed that their teeth are arranged in a way that works as an array or antenna to receive the incoming sound and make it easier for them to pinpoint the exact location of an object. The dolphin's sense of touch is also well-developed, with free nerve endings being densely packed in the skin, especially around the snout, pectoral fins and genital area. However, dolphins lack an olfactory nerve and lobes and thus are believed to have no sense of smell, but they can taste and do show preferences for certain kinds of fish. Since dolphins spend most of their time below the surface normally, just tasting the water could act in a manner analogous to a sense of smell.Though most dolphins do not have any hair, they do still have hair follicles and it is believed these might still perform some sensory function, though it is unclear what exactly this may be. The small hairs on the rostrum of the Boto river dolphin are believed to function as a tactile sense however, possibly to compensate for the Boto's poor eyesight.

Behaviour

Dolphins are often regarded as one of Earth's most intelligent animals, though it is hard to say just how intelligent dolphins are, as comparisons of species' relative intelligence are complicated by differences in sensory apparatus, response modes, and nature of cognition. Furthermore, the difficulty and expense of doing experimental work with large aquatics means that some tests which could yield meaningful results still have not been carried out, or have been carried out with inadequate sample size and methodology. Dolphin behaviour has been studied extensively by humans however, both in captivity and in the wild. See the cetacean intelligence article for more details.

Social behaviour

Dolphins are social, living in pods (also called "schools") of up to a dozen individuals. In places with a high abundance of food, pods can join temporarily, forming an aggregation called a superpod; such groupings may exceed a thousand dolphins. The individuals communicate using a variety of clicks, whistles and other vocalizations. They also use ultrasonic sounds for echolocation. Membership in pods is not rigid; interchange is common. However, the cetaceans can establish strong bonds between each other. This leads to them staying with injured or ill individuals, even actively helping them to breathe by bringing them to the surface if needed.^[15] This altruistic behaviour does not appear to be limited to their own species however. A dolphin in New Zealand that goes by the name of Moko has been observed to seemingly help guide a female Pygmy Sperm Whale together with her calf out of shallow water where they had stranded several times. They have also been known to seemingly protect swimmers from sharks by swimming circles around the swimmers or charging the sharks to make them go away.^{[citation needed]}

Dolphins also show cultural behaviour, something long believed to be a quality unique to humans. In May 2005, a discovery was made in Australia which shows this cultural aspect of dolphin behaviour: Some dolphins, such as the Indo-Pacific Bottlenose Dolphin (Tursiops aduncus) teach their young to use tools. The dolphins break sponges off and cover their snouts with them thus protecting their snouts while foraging. This knowledge of how to use a tool is mostly transferred from mothers to daughters, unlike simian primates, where the knowledge is generally passed on to both sexes. The technology to use sponges as mouth protection is not genetically inherited but a taught behaviour. Another such behaviour was discovered amongst river dolphins in Brazil, where some male dolphins apparently use objects such as weeds and sticks as part of a sexual display.

Dolphins are known to engage in acts of aggression towards each other. The older a male dolphin is, the more likely his body is covered with scars ranging in depth from teeth marks made by other dolphins. It is suggested that male dolphins engage in such acts of aggression for the same reasons as humans: disputes between companions or even competition for other females. Acts of aggression can become so intense that targeted dolphins are known to go into exile, leaving their communities as a result of losing a fight with other dolphins.

Male Bottlenose Dolphins have been known to engage in infanticide. Dolphins have also been known to kill porpoises for reasons which are not fully understood, as porpoises generally do not share the same fish diet as dolphins and are therefore not competitors for food supplies.

`Feeding

Various methods of feeding exist, not just between species but also within a species. Various methods may be employed, some techniques being used by only a single dolphin population. Fish and squid are the main source of food for most dolphin species, but the False Killer Whale and the Killer Whale also feed on other marine mammals.

One feeding method employed by many species is herding, where a pod will control a school of fish while individual members take turns plowing through the school, feeding. The tightly packed school of fish is commonly known as a bait ball. Coralling is a method where fish are chased to shallow water where they are more easily captured. In South Carolina, the Atlantic Bottlenose Dolphin takes this one step further with what has become known as strand feeding, where the fish are driven onto mud banks and retrieved from there. In some places, Orcas will also come up to the beach to capture sea lions. Some species also whack fish with their fluke, stunning them and sometimes sending fish clear out of the water.

Reports of cooperative human-dolphin fisheries date back to the ancient Roman author and natural philosopher Pliny the Elder. A modern human-dolphin fishery still takes place in Laguna, Santa Catarina, Brazil. Here, dolphins drive fish towards fishermen waiting along the shore and give them a signal when they can cast their nets. The dolphins then feed off the fish that manage to escape the nets.

Vocalizations

Dolphins are capable of making a broad range of sounds using nasal airsacs located just below the blowhole. Roughly three categories of sounds can be identified however; frequency modulated sounds which are usually just called whistles; burst-pulsed sounds and clicks. Whistles are used by dolphins to communicate, though the nature and extent of their ability to communicate in this way is not known. Research has shown however that at least some dolphin species are capable of sending identity information to each other using a signature whistle; a whistle that refers specifically to the identity of a certain dolphin. The burst-pulsed sounds are also used for communication, but again the nature and extent of communication possible this way is not known. The clicks are directional and used by dolphins for echolocation and are often in a short series called a click train, the rate increasing when approaching an object of interest. Dolphin echolocation clicks are amongst the loudest sounds made by animals in the sea.

Jumping and playing

Dolphins occasionally leap above the water surface, sometimes performing acrobatic figures (e.g. the Spinner Dolphin). Scientists are not always quite certain about the purpose of this behaviour and the reason for it may vary; it could be to locate schools of fish by looking at above-water signs like feeding birds, they could be communicating to other dolphins to join a hunt, attempting to dislodge parasites, or simply doing it for fun.

Play is a fairly important part of dolphins' lives, and they can be observed playing with seaweed or play-fighting with other dolphins. At times they also harass other local creatures, like seabirds and turtles. Dolphins also seem to enjoy riding waves and frequently 'surf' coastal swells and the bow waves of boats. Occasionally, they're also willing to playfully interact with human swimmers.

Sleeping

Because dolphins need to come up to the surface to breathe and have to be alert for possible predators, they do not sleep in the same way land mammals do. Generally, dolphins sleep with only one brain hemisphere in slow-wave sleep at a time, thus maintaining some amount of consciousness required to breathe and keeping one eye open to keep a watch out for possible threats. The earlier stages of sleep can be observed in both hemispheres of the brain, however.

However, in captivity, dolphins have been observed to seemingly enter a fully asleep state where both eyes are closed and the animal does not respond to mild external stimuli, respiration being automatic with a tail kick reflex keeping the blowhole above the water. If not needed to keep the blowhole above the water, the tail kick reflex may subside. Dolphins kept unconscious using anesthetics initially show a similar tail kick reflex. Though a similar state has been observed with wild Sperm Whales, it is not known if this state is ever reached in the wild amongst any dolphin species.

Mythology

Dolphins have long played a role in human culture. Dolphins are common in Greek mythology and there are many coins from the time which feature a man or boy riding on the back of a dolphin. The Ancient Greeks treated them with welcome; a ship spotting dolphins riding in their wake was considered a good omen for a smooth voyage. In Hindu mythology, the Ganges River Dolphin is associated with Ganga, the deity of the Ganges river.

Therapy

Dolphins are an increasingly popular choice of animal-assisted therapy for psychological problems and developmental disabilities. For example, a 2005 study with 30 participants found it was an effective treatment for mild to moderate depression. However, this study was criticized on several grounds; for example, it is not known whether dolphins are more effective than common pets. Reviews of this and other published dolphin-assisted therapy (DAT) studies have found important methodological flaws and have concluded that there is no compelling scientific evidence that DAT is a legitimate therapy or that it affords any more than fleeting improvements in mood.

Military

A number of militaries have employed dolphins for various purposes from finding mines to rescuing lost or trapped humans. Such military dolphins, however, drew scrutiny during the Vietnam War when rumors circulated that dolphins were being trained by the United States Navy to kill Vietnamese divers. Dolphins are still being trained by the United States Navy however as part of the U.S. Navy Marine Mammal Program. The Russian military is believed to have closed its marine mammal program in the early 1990s. In 2000 the press reported that dolphins trained to kill by the Soviet Navy had been sold to Iran.

Must for obligation, mustn't for prohibition:

Must is a modal verb.  You use must to talk about something you're obliged or strongly advised to do.
You often use it when you talk about safety instructions.

You use must not, (mustn't) to talk about something you aren't allowed to do or you're strongly advised not to do.

For strong prohibition you use must never.

Must and have to have almost the same meaning.
You usually use must when the obligation comes from one of the speakers.

You usually use have to when the obligation comes from a third person.
You often use it when you talk about rules.

Choose the correct answer.

Gerunds and infinitives can both be used as subjects, subject complements, and direct objects of verbs. The choice of whether to use a gerund or infinitive as a subject, subject complement, or object of some verbs is left to the speaker/writer. This choice can indicate shades of meaning.

But the choice between which to use as a direct object is sometimes dictated by the verb, leaving no choice. Which verbs can be followed by gerunds, which by infinitives, (and which by either) must be memorized. In addition, some verbs require that an infinitive object have a different subject (agent) from that of the first verb, for others no other agent is possible, and for some both are possible. Again, these must be memorized. The general meanings associated with gerunds and infinitives can offer clues, but do not always predict which forms are possible.

Remember, the question here concerns verbs which control gerunds and infinitives as their objects. Of course, both infinitives and gerunds can follow an unlimited number of verbs for other reasons. For example, infinitives can also follow verbs to show purpose, in reduced adjective or adverb clauses, or with other meanings. Gerunds with noun modifiers can be the objects of many different verbs. And present participles, which may look like gerunds, are not controlled by preceding verbs. And remember that noun clauses can also be used as objects of many of these same verbs

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Verbs Followed by Gerund and/or Infinitive