Directions:
Read the following text. Choose the best word(s) for each numbered blank and mark [A], [B], [C] or [D] on ANSWER SHEET 1 (10 points)
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. [A] although
[B] as
[C] but（C）
[D] while
2. [A] above
[B] unlike
[C] excluding（B）
[D] besides
3. [A] limited
[B] committed
[C] dedicated（A）
[D] confined
4. [A] catching
[B] ignoring
[C] missing（C）
[D] tracking
5. [A] anyway
[B] though
[C] instead（B）
[D] therefore
6. [A] even if
[B] if only
[C] only if（A）
[D] as if
7. [A] distinguishing
[B] discovering
[C] determining（D）
[D] detecting
8. [A] diluted
[B] dissolved
[C] determining（A）
[D] diffused
9. [A] when
[B] since
[C] for（D）
[D] whereas
10. [A] unusual
[B] particular
[C] unique（B）
[D] typical
11. [A] signs
[B] stimuli
[C] messages（C）
[D] impulses
12. [A] at first
[B] at all
[C] at large（A）
[D] at times
13. [A] subjected
[B] left
[C] drawn（D）
[D] exposed
14. [A] ineffective
[B] incompetent
[C] inefficient（C）
[D] insufficient
15. [A] introduce
[B] summon
[C] trigger（D）
[D] create
16. [A] still
[B] also
[C] otherwise（B）
[D] nevertheless
17. [A] sure
[B] sick
[C] aware（C）
[D] tired
18. [A] tolerate
[B] repel
[C] neglect（D）
[D] notice
19. [A] available
[B] reliable
[C] identifiable（A）
[D] suitable
20. [A] similar to
[B] such as
[C] along with（B）
[D] aside from
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