People have been talking about health for a long time because people know the importance of it. People's understanding of health also becomes deeper with the progress in scientific research. Recently the term "health" has come to have a wider meaning than it used to. It no longer means just the absence of illness. Today, health means the well-being of your body, your mind and your relationship with other people. This new concept of health is closely related to another term-quality of life. Quality of life is the degree of overall satisfaction that a person gets from life.

　　Why has the emphasis of health shifted from the absence of disease to a broader focus on the quality of a person's life? One reason for this has to do with the length and conditions of life that people can now expect. Medical advances have made it possible for people today to live longer, healthier lives. Imagine for a moment that you were born in the year 1900. You could have expected on average to live until about the age of 47. In contrast, if you were born in the year 1999, you could expect to live to the age of 75.

1.________ leads to people's deeper understanding of health.

A．Common knowledge

B．Progress in scientific research

C．Better conditions of living

D．Quality of life

2.The emphasis of health has shifted nowadays because _________.

A．people enjoy better conditions of living and they can live longer

B．people pay more attention to their physical health, not their mental health

C．people have realized the importance of mental well-being

D．people are inspired by medical advances

3.We can infer from the passage __________.

A．nowadays the emphasis of health has a broader focus because of improvements in the quality of food

B．the overall quality of people's lives improved greatly in the 20th century

C．those who never fall ill are the truly healthy people

D．those who were born before 1900 could not have lived until now

4.This passage is mainly about __________.

A．different understandings of the term "health"

B．improving the quality of life

C．the importance of quality living

D．people's expectations of a long and healthy life

We have known for a long time that flowers of different plants open and close at different time of day. This is so familiar that there seems to be no need to ask the reason for it. Yet no one really understands why flowers open and close like this at particular times. The process (过程) is not as simple as we might think, as recent experiments have shown. In one study, flowers were kept in constant (连续的) darkness. We might expect that the flowers, without any information about the time of day, did not open as they normally do. In fact, they continued to open at their usual time. This suggests that they have some mysterious (神秘的) way of knowing the time. Their sense of time does not depend on information from the outside world; it is, so to speak, inside them, a kind of “inner clock”. This discovery (发现) may not seem to be very important. However, it was later found that not just plants but also animals —including man —have this “inner clock” which controls the working of their bodies and influences (影响) their activities. Men, then, are also influenced by this mysterious power. Whether we wish it or not, it affects such things in our life as our need for sleep, our need for food. In the past, this did not matter very much because people lived in natural condition. In the modern world, things are different; now there are spacemen, airplane pilots and, in ordinary life, a lot of people who have to work at night. It would be very useful, then, to know more about the “inner clock”. Such ordinary things as flowers might help us understand more about ourselves.

46. A recent experiment showed that ________________.  

A. different flowers open and close at different times of day  

B. for their opening and closing, flowers do not need information from the outside world  

C. flowers are influenced by weak light even when they are in a dark room  

D. flowers can be used for telling the time

47. Further study of the “inner clock” will be useful because ______________.   

A. it might help us in some way   

B. we do not yet understand plants and animals well enough   

C. the number of spacemen and airplane pilots is fast increasing   

D. we should try to live more naturally than we do now

48. The “inner clock” _________________________.   

A. is an unimportant discovery           B. is only found in animals   

C. has not been understood by far         D. has an effect on human life

49. Kept in constant darkness, flowers ________________________.   

A. will not open or close as usual           

B. will not open any longer   

C. will open as they do in natural conditions  

D. will always remain in full blossom (开花)

50. ____________ have a mysterious power of knowing time without information from the outside world.   

A. Animals including man as well as plants     

B. All living things except man   

C. Flowers are the only things in the world that    

D. Neither animals nor plants