Eijkman noticed that the chickens began to recover on the new diet. He began to consider the possibility that eating unpolished rice somehow prevented or cured "beri-beri" —— even that a lack of some element in the husk might be the cause of the disease. Indeed this was the case. The element needed to prevent "beri-beri" was shortly afterwards isolated from rice husks and is now known as vitamin B. Nowadays, this terrible disease is much less common thanks to our knowledge of vitamins.
6. A good mixed diet ．
A. normally contains enough vitamins
B. still needs special provision of vitamins
C. is suitable for losing weight
D. is composed of fruits and vegetables
7. The disease "beri-beri" ．
A. kills large numbers of Eastern peoples
B. is a vitamin deficiency （缺乏） disease
C. is caused by diseased deer
D. can be caught from diseased chickens
8. The chickens Eijkman noticed in the hospital yard ．
A. couldn't digest the polished deer
B. proved "beri-beri" is caused by germs
C. were later cooked for the patients' food
D. were suffering from "beri-beri"
9. According to Eijkman, polished rice ．
A. was cheaper than unpolished rice
B. was less nourishing （有营养的） than unpolished rice
C. was more nourishing than unpolished rice
D. cured "beri-beri"
10. The chemical substance missing from polished rice ．
A. was vitamin B
B. did not affect the chickens
C. was named the Eijkman vitamin
D. has never been accurately identified
Questions 11 to 15 are based on the following passage:
I hear many parents complain that their teenage children are rebelling. I wish it were so. At your age you ought to be growing away, from your parents. You should be learning to stand on your own feet. But take a good look at the present rebellion. It seems .that teenagers are all taking the same way of showing that they disagree with their parents. Instead of striking out boldly on their own, most of them are holding one another's hands for reassurance （放心）。
They claim they want to dress as they please. But they all wear the same clothes. They set off in new directions in music. But they all end up listening to the same record. Their reason for thinking or acting in such a way is that the crowd is doing it. They have come out of their cocoon （茧） into a larger cocoon.
（80） It has become harder and harder for a teenager to stand up against the popularity wave and to go his or her own way. Industry has firmly carved out a market for teenagers. These days every teenager can learn from the advertisements what a teenager should have and be. This is a great barrier for the teenager who wants to find his or her own path.
But the barrier is worth climbing over. The path is worth following. You may want to listen to classical music instead of going to a party. You may want to collect rocks when everyone else is collecting records. You may have some thoughts that you don't care to share at once with your classmates. Well, go to it. Find yourself. Be yourself. Popularity will come —— with the people who respect you for who you are. That's the only kind of popularity that really counts.
11. The author's purpose in writing this passage is to tell ．
A. readers how to he popular with people around
B. teenagers how to learn to make a decision for themselves
C. parents how to control and guide their children
D. people how to understand and respect each oth~
12. According to the author, many teenagers think they are brave enough to act on their own, but in fact most of them ．
A. have much difficulty understanding each other
B. lack confidence
C. dare not cope with any problems alone
D. are very much afraid of getting lost
13. Which of the following is NOT true according to the passage？
A. There is no popularity that really counts.
B. Many parents think that their children are challenging their authority.
C. It is not necessarily bad for a teenager to disagree with his or her classmates.
D. Most teenagers are actually doing the same.
14. The author thinks of advertisements as to teenagers.
A. inevitable
B. influential
C. instructive
D. attractive
15. The main idea of the last paragraph is that a teenager should
