We can help control weight by watching our food intake, the exercise we get, or both.
   To keep the same weight, we must balance calories(卡路里) found in food and those used by the body. To lose weight, we must get fewer calories from food than the body uses. To gain weight, we must get more.
   It takes about 3,500 extra calories to make a pound of stored fat. For each pound to be gained or lost, there must be 3,500 calories more or 3,500 calories less in the diet than the body uses.
   If you plan to lose or gain weight by watching the amount of food eaten without changing activities, the rate of loss or grain will depend on the number of calories you subtract from or add to your diet each day.
   For example, to lose two pounds a week a person would have to take in 7,000 calories fewer each week than the body uses. Or one would need 1,000 calories fewer each day. A person whose caloric need is 2,400 calories a day would cut down to 1,400 calories a day. It’s a good idea not to go below 1,200 calories a day without a doctor’s supervision(指导), because it is hard to get the minerals and vitamins we need from foods when diets have fewer calories than this.
   The same figure---3,500 calories per pound of stored fat---can be used as a general guide in planning meals to add or maintain weight. However, there are so many differences in people, in food, and in the amount of energy used in carrying out activities that the figure may not be just right for you. Leisure time probably offers the best chance for increased or decreased activities for weight control.
   Long hours spent in hard exercise are not necessary to keep weight under control. For many persons it is recommended. Regular, less strenuous(费力的)exercise can be effective for those who want to lose or maintain weight while eating enough food to be satisfied.

1.The author states that one may lose weight most rapidly by ____________.

A. increasing exercise and decreasing food intake

B. increasing exercise and increasing food intake

C. decreasing exercise and decreasing food intake

D. decreasing exercise and increasing food intake

2.For a person on a diet, a doctor would probably advise him____________.

A. to have extra sleep

B. to take vitamin pills

C. to drink more water

D. to do moderate exercise

3.To keep weight under control, one should_________.

A. exercise strenuously for several hours a day

B. develop a regular schedule of exercise

C. participate in several sports

D. eat less and do hard exercise

4.The author implies that weight control is__________.

A. an area of great misunderstanding

B. based on luck

C. harmful

D. a matter of self-control

5.The purpose of the passage is _______________.

A. to persuade the reader not to eat sweets

B. to identify one cause of gaining weight

C. to prove that weight can be  regulated

D. to show the reader how to lose weight

                      
　　There are two factors which determine an individual’s intelligence. The first is the sort of brain he is born with. Human brains differ considerably, some being more capable than others. But no matter how good a brain he has to begin with, an individual will have a low order of intelligence unless he has opportunities to learn. So the second factor is what happens to the individual—the sort of environment in which he is reared(培养). If an individual is handicapped(使不利) environmentally, it is likely that his brain will fail to develop and he will never attain the level of intelligence of which he is capable.
　　The importance of environment in determining an individual’s intelligence can be demonstrated by the
case history of the identical twins(同卵双胞胎), Peter and Mark. Being identical, the twins had identical brains at birth, and their growth processes were the same. When the twins were three months old, their parents died, and they were placed in separate foster homes. Peter was reared by parents of low intelligence in an isolated community with poor educational opportunities. Mark was reared in the home of well-to-do parents who had been to college. He was read to as a child, sent to good schools, and given every opportunity to be stimulated intellectually. This environmental difference continued until the twins were in their late teens, when they were given tests to measure their intelligence. Mark’s I.Q.(智商) was 125, twenty-five points higher than the average and forty points higher than his identical brother. Given equal opportunities, the twins, having identical brains, would have tested at roughly the same level.

1.This passage can best be titled______________.

A. Measuring Your Intelligence

B. Intelligence and Environment

C. The Case History of Peter and Mark

D. How the Brain influences Intelligence

2.The main idea of this passage is that__________.

A. the brain a person is born with is important in determining his intelligence

B. environment is crucial in determining a person’s intelligence

C. a person who is handicapped environmentally will never attain the level of intelligence of which he is capably

D. persons having identical brain will have roughly the same intelligence

3.According to the passage, the average I. Q. is__________.

A. 85                     B. 100

C. 110                    D. 125

4.The case history of the twins appears to support the conclusion that__________.

A. individuals with identical brains seldom test at the same level

B. an individual’s intelligence is determined solely by his environment

C. children reared under average conditions posses average intelligence

D. lack of opportunity delays the growth of intelligence.

5.This passage suggests that an individual’s I.Q.__________

A. can be predicted at birth

B. is inherited from his parents

C. stays the same throughout his life

D. can be increased by education

  Water on the earth is being continuously recycled in a process known as the hydrologic cycle(水循环). The first step of the cycle is the evaporation of water in the oceans. Evaporation is the process of water turning into vapor, which then forms clouds in the sky. The second step is the water returning to the earth in the form of either rain, snow or ice. When the water reaches the earth’s surface, it runs off into the rivers, lakes and the ocean, where the cycle begins again.
  Not all water, however, stays on the surface of the earth in the hydrologic cycle. Some of it flows slowly into the ground through infiltration(渗入) and collects under the earth’s surface as ground water. This ground water is extremely important to life on earth since 95% of the earth’s water is in the oceans, and is too salty for humans or plants. Of the 5%on land, only 0.05% is above ground in rivers or lakes. The rest is underground water. This ground water is plentiful and dependable, as it doesn’t depend on seasonal rain or snow. It is the major source of water for many cities. But as the population increases and the need for water also increases, the ground water in some areas is getting dangerously low. Added to this problem is an increasing amount of pollution that flows into the ground water. In the future, with an increasing population and more poisonous waste, t