59A.typeB.variationC.methodD.process

Whether or not exercise adds to the length of life, it is common experience that a certain amount of regular exercise -(51) health and contributes a feeling of well-being. Furthermore, exerise _(52) involves play and recreation(娱乐), and relieves nervous tension and mental fatigue in so _(53) is not only pleasant but beneficial.

How much and what kind of exercise one should _(54) merits careful consideration The growing child and the normal young man and young woman thrill(兴奋) with the strenuousc剧烈的) sports. They fatigue to the _(55) of exhaustion but recover promptly with a period of rest. But not so with those of middle age and beyond. For them moderation is _(56) vital importance.

Just how much exercise a person of a given age can safely take is a question hard to (57). Individual variability is too great to permit of generalization A game of tennis may be perfectly safe for one person of forty but folly (愚蠢) for another. The sage _(58) for exercise depends on the condition of the heart, the condition of the muscles, the _(59) of exercise, and the reg- ularity with which it is taken. Two general suggestions, however, will _(60) as sound advice for anyone. The first is that the _ _(61) of the heart and general health should be determined pe- riodically by careful, thorough physical examinations. The other is that exercise should be (62) below the point of physical exhaustion.

What type of exercise one should _(63) depends upon one's physical condition. Young people can safely enjoy competitive sports, but most older persons do better to limit themselves to less strenuous (64). Walking, swimming, skating are among the sports that one can enjoy and safely _ (65) in throughout life. Regularity is important if one is to get the most enjoyment and benefit out of exercise.

51

A.improves

B.damages

C.enjoys

D.provides

A.covered

B.reduced

C.moved

D.destroyed

The human body is truly amazing. It allows us to sense the world around us, to do work and have fun, and to move from place to place. In fact, the human body does its work so well that most people don't think about it very much - until they get sick.

The germs (致病菌) that make people sick are everywhere. You can't see them, but they're there. They're sitting on your desk. They're hiding on your computer's keyboard. They're even in the air that you are breathing. There are two types of germs: viruses and bacteria（细菌）. Viruses are germs that can only live inside animals or plants. Viruses cause illnesses such as flu and measles（麻疹）. Bacteria are tiny creatures. Some bacteria are good. They can help your stomach break down food. Other bacteria aren't so good. They can make you sick. Bacteria can cause sore throats（喉痛） and ear infections.

How can you'stop these tiny invaders from making you sick？ Your skin is the first defense against germs. You can prevent some illnesses simply by washing, with soap and water. But germs can still enter the body through small cuts in the skin or through the mouth, eyes, and nose.

Once germs are inside your body, your immune(免疫的) system tries to protect you. It looks for and destroys germs. How does it do that？ Special cells patrol your body. Some of these cells actually eat germsl Other cells make antibodies. An antibody sticks to a germ. There is a different antibody for each kind of germ. Some antibodies keep germs from making you sick. Others help your body find and kill germs. After a germ is destroyed, the antibodies stay in your body. They protect you if the same kind of germ comes back. That way you will not get the same illness twice.

You can keep your body healthy by eating a nutritious (有营养的 ) diet to make your immune sys- tem strong. You can also help your immune system fight germs by getting vaccinated（接种）. Vaccines are medicines. They contain germs that have been killed or weakened. The dead germs can't make you sick. Instead, they cause your body to make antibodies. If the same germ ever shows up again, then your antibodies attack it.

Viruses can only live inside people or animals

A.Right

B.Wrong

C.Not mentioned

A.participants

B.observers

C.listeners

D.actors

A.covered

B.destroyed

C.reduced

D.moved

A.hate

B.need

C.love

D.pity

A.Right

B.Wrong

C.Not mentioned

A.Right

B.Wrong

C.Not mentioned

A.20 percent Americans want smaller portions.

B.57 percent Americans earn $ 150, 000 per year.

C.Low-income American prefer large portion

D.23 percent Americans earn less than $ 25, OOOper year.

Citiesaround the world are working to protect their urban forests. Some urban forestsare parks, andsome are just streets with a lot of trees. But all urban forestshave many good effects on the environment. (47) They also stop the noisefrom heavy traffic. They even make the weather better because theymake the air3-5 degrees cooler, and they stop strong winds.

Urbanforests also have many good effects on people. They make the city morebeautiful. In a crowded ar-ea, they give people a place to relax and spend timein nature. (48)

In somecountries, people are starting new urban forests. InEngland,there are now l. 3 milliontrees in an urban forest called Thames Chase, east ofLondon. It wasstarted in 1990, and it has grownvery fast. Walking and bicycle clubs use theforest, and there are programs for children and artists. (49)

Someolder cities don't have space for a big urban forest, but planting trees on thestreets makesthe city better. Scientists found that commuters (通勤人员) feel more relaxedwhen they can see trees.Trees are even good for business. _ (50)In the future, urban forests willbecome even moreimportant as our cities grow bigger. In the megacities (超大城市) of tomorrow, peoplewill need moregreen space to live a comfortable life. Planting trees today willmake our lives better in the future.

A.Peoplespend more time at shopping centers that have trees.

B. In hot countries, urban forests are coolplaces for walking and other healthy exercises.

C.Butyou are not in rural area.

D.Trees take pollution out of the air

E.In2033, it will have 5 million trees.

F.It has many kinds of birds in the country