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Recent research has claimed that an excess of positive ions in the air can have an ill effect on people’s physical or psychological health. What are positive ions? Well, the air is full of ions, electrically charged particles,
and generally there is a rough balance between the positive and the negative charged. But sometimes this balance becomes disturbed and a larger proportion of positive ions are found. This happens naturally before thunderstorm, earthquakes
when winds such as the Mistral, Hamsin or Sharav are blowing in certain countries. Or it can be caused by a build-up of static electricity indoors from carpets or clothing made of man-made fibres, or from TV sets, duplicators or
computer display screens.
When a large number of positive ions are present in the air many people experience unpleasant effects such as headaches, fatigue, irritability, and some sensitive people suffer nausea or even mental disturbance. Animals
are also affected, particularly before earthquakes, snakes have been observed to come out of hibernation, rats to flee from their burrows, dogs howl and cats jump about unaccountably. This has led the US Geographical Survey to fund a
network of volunteers to watch animals in an effort to foresee such disasters before they hit vulnerable areas such as California.
Conversely, when large numbers of negative ions are present, then people have a feeling of well-being. Natural conditions that produce these large amounts are near the sea, close to waterfalls or fountains, or in any place where water is sprayed, or forms a spray. This probably accounts for the beneficial effect of a holiday by the sea, or in the mountains with tumbling streams or waterfalls.
To increase the supply of negative ions indoors, some scientists recommend the use of ionisers: small portable machines, which generate negative ions. They claim that ionisers not only clean and refresh the air but also improve the health of people sensitive to excess positive ions. Of course, there are the detractors, other scientists, who dismiss such claims and are skeptical about negative/positive ion research. Therefore people can only make up their own minds by observing the effects on themselves, or on others, of a negative rich or poor environment. After all it is debatable whether depending on seismic readings to anticipate earthquakes is more effective than watching the cat.
1.What effect does exceeding positive ionization have on some people?
A.They think they are insane.
B.They feel rather bad-tempered and short-fussed.
C.They become violently sick.
D.They are too tired to do anything.
2.In accordance with the passage, static electricity can be caused by___.
A.using home-made electrical goods.
B.wearing clothes made of natural materials.
C.walking on artificial floor coverings.
D.copying TV programs on a computer.
3.A high negative ion count is likely to be found___.
A.near a pound with a water pump.
B.close to a slow-flowing river.
C.high in some barren mountains.
D.by a rotating water sprinkler.
4.What kind of machine can generate negative ions indoors?
A.Ionisers.
B.Air-conditioners.
C.Exhaust-fans
D.Vacuum pumps.
5.Some scientists believe that___.
A.watching animals to anticipate earthquakes is more effective than depending
on seismography.
B.the unusual behavior of animals cannot be trusted.
C.neither watching nor using seismographs is reliable.
D.earthquake
The food we eat seems to have profound effects on our health. Although
science has made enormous steps in making food more fit to eat, it has , atthe
same time, made many foods unfit to eat. Some research has shown that perhaps
eighty percent of cancer is related to the diet as well, especially cancer the
colon . Different cultures are more prone to contract certain illnesses because
of the food that is characteristic in these cultures. That food related to
llness is not a new discovery. In 1945 , government researchers realized that
itrates and nitrites, commonly used to preserve color in meats, and other food
dditives, caused cancer. Yet, these carcinogenic additives remain in our food,
nd it becomes more difficult all the time to know which things on the pack ging
labels of processed food are helpful or harmful.The additives which we eat are
not all so direct. Farmers often give penicillin to beef and poultry, and
because of this, penicillin has been found in the milk of treated cows.
Sometimes similar drugs are administered to animals not for medicinal purposes,
but for financial reasons. The farmers are simply trying to fatten the animals
in order to obtain a higher price on the market. Although the Food and Drug
Administration (FDA) has tried repeatedly to controlthese procedures, the
practices continue.
48. What is the main topic of the passage?
A. Food and our health
B Food and additives
C. Food and cancer
D Food and culture
49 All of the following statements are true EXCEPT_______.
A Forty percent of cancer is caused by problems related to food.
B Researchers have known about the potential danger of food additivesfor many
years
C. We eat some of the food additives directly and some indirectly
D Drugs are always given to animals for medicinal purposes
50. Why do farmers give drugs to their animals?
A. to speed up the growth of animals
B To make theanimals fatter
C to make the animals ’ meat fit to eat
D To make the animals’ meat rich in nutrients
51. It can be inferred from the passage that_________.
A scientist have made all the food fit to eat
B only in recent years have people found that the food is related to one’s
illness
C all kinds of cancer are related to the diet
D some additives are harmful to our health
52. The word “ this ”in the second sentence of paragraph 2 most
probablyrefers to __________.
A farmer
B penicillin
C beef and poultry
D the fact that farmers often give penicillin to a beef
