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Apples are usually sold by ________ weight and eggs are sometimes sold by ________ dozen.
A. the; the B. /;a
C. /; the D. the; a
查看习题详情和答案>>Number sense is not the ability to count. It is the ability to recognize a 1 in number. Human beings are born with this ability. 2 ，experiments show that many animals are, too. For example, many birds have good number sense. If a nest has four eggs and you remove one, the bird will not 3 . However, if you remove two, the bird 4 leaves. This means that the bird knows the 5 between two and three.
Another interesting experiment showed a bird's 6 number sense. A man was trying to take a photo of a crow(乌鸦)that had a nest in a tower, but the crow always left when she saw him coming. The bird did not 7 until the man left the tower. The man had an 8 .He took another man with him to the tower. One man left and the other stayed, but they did not 9 the bird. The crow stayed away until the second man left, too. The experiment was 10 with three men and then with four men. But the crow did not return to the nest until all the men were 11 .It was not until five men went into the tower and only four left that they were 12 able to fool the crow.
How good is a human's number sense? It's not very good. For example, babies about fourteen months old almost always notice if something is taken away from a 13 group. But when the number goes beyond three or four, the children are 14 fooled.
It seems that number sense is something we have in common with many animals in this world, and that our human 15 is not much better than a crow's.
1. A. rise B. pattern C. change D. trend
2. A. Importantly B. Surprisingly C. Disappointedly D. Fortunately
3. A. survive B. care C. hatch D. notice
4. A. generally B. sincerely C. casually D. deliberately
5．A. distance B. range C. different D. interval
6．A. amazing B. annoying C. satisfying D. disturbing
7. A. relax B. recover C. react D. return
8. A. appointment B. excuse C. idea D. explanation
9. A. fool B. hurt C. catch D. kill
10.A. repo B. repeated C. designed D. approved
11.A. confused B. gone C. tired D. drunk
12.A. gradually B. luckily C. strangely D. finally
13. A. single B. small C. local D. new
14. A. seldom B. temporarily C. merely D. often
15. A. sight B. nature C. ability D. belief
查看习题详情和答案>>Apples are usually sold by ________ weight and eggs are sometimes sold by ________ dozen.
A. the; the B. /;a
C. /; the D. the; a
查看习题详情和答案>>Zinc(锌) is one of about 20 elements necessary for good health. It is present in the body in a very small amount but makes it possible for important chemical actions to be carried out in cells. Scientists are just beginning to discover how zinc and other elements work.
Researchers first studied zinc as a way to speed recovery. Dr. Waltor Powys formerly with the United States Air Force noted that the laboratory animals recovered faster when some matters were added to their food. One of these matters was zinc. Dr. Powys later tested the zinc treatment on an American airman recovering from medical operations. The airman who received zinc sulphate(硫酸盐) recovered in half of the usual time. Other doctors studied persons who had a number of strange disorders. The doctors learned that all of these problems were caused by lack of zinc in the body. They treated these disorders successfully by giving the patients zinc sulphate.
The amount of zinc in the body can be found by examining blood and hair. A lack of this important element is not uncommon among people in both industrial and developing countries. Zinc is found in most high protein(蛋白质) foods such as meat, milk, fish and eggs. It is also found in whole grains. But many people do not eat enough of these food. Food markets should add these elements so that more people could get needed amount of these necessary matters.
1. Which of the following statements is true?
A. Scientists found how zinc works a long time ago.
B. People need a large amount of zinc to be healthy.
C. Zinc allows important chemical actions to take place in cells.
D. Zinc must be used in the course of medical operation.
2. One of the results from the study of zinc is that _______.
A. there’s only a little zinc in the human body
B. food rich in protein contains more zinc
C. some physical problems are caused by lack of zinc
D. any patient who receives zinc sulphate gets well immediately
3. The best title for the passage may be _______.
A. A New Discovery B. Zinc and Health
C. How Zinc Works D. Add Zinc to Your Food
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