2016年考研英语完型填空强化练习:The human nose
The human nose is an underrated tool. Humans are often thought to be insensitive smellers compared with animals, __1__ this is largely because, __2__ animals, we stand upright. This means that our noses are __3__ to perceiving those smells which float through the air, __4__ the majority of smells which stick to surfaces. In fact, __5__, we are extremely sensitive to smells, __6__ we do not generally realize it. Our noses are capable of __7__ human smells even when these are __8__ to far below one part in one million. Strangely, some people find that they can smell one type of flower but not another, __9__ others are sensitive to the smells of both flowers. This may be because some people do not have the genes necessary to generate __10__ smell receptors in the nose. These receptors are the cells which sense smells and send __11__ to the brain. However, it has been found that even people insensitive to a certain smell __12__ can suddenly become sensitive to it when __13__ to it often enough. The explanation for insensitivity to smell seems to be that brain finds it __14__ to keep all smell receptors working all the time but can __15__ new receptors if necessary. This may __16__ explain why we are not usually sensitive to our own smells we simply do not need to be. We are not __17__ of the usual smell of our own house but we __18__ new smells when we visit someone else’s. The brain finds it best to keep smell receptors __19__ for unfamiliar and emergency signals __20__ the smell of smoke, which might indicate the danger of fire.1. although as but while
2. above unlike excluding besides
3. limited committed dedicated confined
4. catching ignoring missing tracking
5. anyway though instead therefore
6. even if if only only if as if
7. distinguishing discovering determining detecting
8. diluted dissolved determining diffused
9. when since for whereas
10. unusual particular unique typical
11. signs stimuli messages impulses
12. at first at all at large at times
13. subjected left drawn exposed
14. ineffective incompetent inefficient insufficient
15. introduce summon trigger create
16. still also otherwise nevertheless
17. sure sick aware tired
18. tolerate repel neglect notice
19. available reliable identifiable suitable
20. similar to such as along with aside from
参考答案：1-5. . . . . 6-10. . . . .
11-15. . . . . 16-20. . . . .
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