When and where he came here _______ yet.

  A. isn’t known    B. aren’t known    C. has not known   D. have not been known

The audience was ____ very young children so there was a lot of noise while the concert was going on.

   A. consisted in      B. made up for        C. consisted of        D. made up of

 A modern city has been set up in   ___    was a wasteland ten years ago.

A. what               B. which             C. that                D. where       

Alice was too surprised to hold her __________.

A. breathed            B. breathing                 C. breathe                    D. breath

   It was once thought that air pollution only affected the area immediately around large cities with factories or heavy automobile traffic. Today we know that although these are the areas with the worst air pollution, the problem is actually worldwide. On several occasions over the past ten years, a heavy cloud of air pollution has covered the entire eastern half of the United States and led to health warning even in rural areas away from any major concentration of big factories or automobile. In fact, the very climate of the entire earth may be affected by air pollution. Some scientist feel that the increasing concentration of carbon dioxide in the air resulting from the burning of coal and oil is creating a "green house" effect--holding in heat reflected from the earth and raising the world's average temperature. If this view is correct and the world's temperature is raised only a few degrees, much of the polar ice will disappear and cities, such as New York, Boston, Miami, and New Orleans will be under water.

   Another view, less widely held, is that increasing particulate matter (顆粒物質(zhì)) in the atmosphere is blocking sunlight and lowering the earth's temperature--a result that would be equally disastrous. A drop of just a few degrees could create something close to new ice age and would make agriculture difficult or impossible in many of our top farming areas. At present we do not know for sure that either of these conditions will happen (though one recent government report prepared by experts in this field concluded that the green house effect is very likely). Perhaps, if we are lucky enough, the two trends will offset each other and the world's temperature will stay about the same as it is now.

72. As far as the green house effect is concerned, the author_________.

   A. shares the same view with the scientist

   B. is not sure that it will happen

   C. thinks it impossible because there is no strong evidence

   D. thinks it will destroy the world soon

73. According to what we read in the passage, _________.

   A. raising the world's temperature only a few degrees would do no harm to life on the earth

   B. lowering the world's temperatures only a few degrees would lead many major farming areas to disaster

   C. the temperature in the countryside will remain permanent in the years to come

   D. the particulate matter in the atmosphere has lowered the world's average temperature

74. The word "offset" in the last sentence means_________.

   A. strengthen      B. worsen     C. balance      D. support

75. This passage is mainly about_________.

   A. the pollution caused by human beings         B. the green house effect

   C. the potential effect of air pollution            D. the possibility of a new ice age

 An economist is____________expert who will know tomorrow why_________things he predicted yesterday didn't happen.

   A. the; \             B. the; the           C. an; the           D. an; \

______________breaks the law should be punished.

He sighed again and the failure in physics seemed to have completely ______ his confidence.

   A. damaged                   B. attacked            C. shocked                   D. struck

       71   It is divided into two types: short term memory and long term memory. Short term memory helps the brain to remember the information from a few seconds to a few minutes, for example, searching a phone number in the phone directory. This type of information is not stored for a long time, and slips from the brain.    72    

      73    There is no exact definition of brain exercises. The key to brain exercises is to stimulate(刺激) the gray cells of our mind. For example, trying out different problem solving exercises can be a good practice for improving the analytical skills of brain.   74   If you regularly exercise it, you will develop a good body, or else you will have an unfit body, and thus, our brain needs exercises regularly. Here are some memory improvement tips for adults:

●Regular exercises help to keep away diseases that are harmful to the memory. Besides, regular exercising improves the feeling of well-being and improves blood circulation to the brain.

●Don't be stressed, as stress holds back the ability of the mind to concentrate. A stress-free mind will collect and store more information that a stressed mind, so avoid being over-stressed. But in modern times people have great pressure from work and life.    75   . Sleep is necessary for keeping the mind and body fit and the side effects of lack of sleep include a lack of concentration.

Ask your doctors for advice on memory.

Developing good sleeping habits helps a lot.

The memory is just like our body in some way.

Memory is the remembering of any information taken in by the brain.

Not all people have the power to recite so many things at a time.

Long term memory, on the other hand, is the memory where we make conscious efforts to keep the information for a long time.

Brain exercises are one of the simplest ways of improving memory power.

—Hey, you are wanted on the phone.

—_________ I’m coming.

A. So what?     B. Hold on a minute.    C. You guessed it.     D. What a shame!