Part II Cloze (10 points)

Directions: There are 20 blanks in the following passage.For each blank there are four choices marked A, B, C and D beneath the passage.You should choose the ONE that best fits into the passage.Then mark the corresponding letter on the Answer Sheet with a single line through the center.

The human nose is an underrated tool.Humans are often thought to be insensitive smellers compared with animals, _21_ this is largely because, _22_ animals, we stand upright.This means that our noses are _23_ to perceiving those smells which float through the air, _24_ the majority of smells which stick to surfaces.In fact, _25_, we are extremely sensitive to smells, _26_ we do not generally realize it.Our noses are capable of _27_ human smells even when these are _28_ to far below one part in one million.

Strangely, some people find that they can smell one type of flower but not another, _ 29_ others are sensitive to the smells of both flowers.This may be because some people do not have the genes necessary to generate _30_ smell receptors in the nose.These receptors are the cells which sense smells and send _31_ to the brain, however, it has been found that even people insensitive to a certain smell _32_ can suddenly become sensitive to it when _33_ to it often enough.

The explanation for insensitivity to smell seems to be that brain finds it _34_ to keep all smell receptors working all the time but can _35_ new receptors if necessary.This may _36_ explain why we are not usually sensitive to our own smells—we simply do not need to be.We are not _37_ of the usual smell of our own house but we _38_ new smells when we visit someone else’s.The brain finds it best to keep smell receptors _39_ for unfamiliar and emergency signals _40_ the smell of smoke, which might indicate the danger of fire.

21.A.although B.as C.but D.while

22.A.above B.unlike C.excluding D.besides

23.A.limited B.committed C.dedicated D.confined

24.A.catching B.ignoring C.missing D.tracking

25.A.anyway B.though C.instead D.therefore

26.A.even if B.if only C.only if D.as if

27.A.distinguishing B.discovering C.determining D.detecting

28.A.diluted B.dissolved C.dispersed D.diffused

29.A.when B.since C.for D.whereas

30.A.unusual B.particular C.unique D.typical

31.A.signs B.stimuli C.messages D.impulses

32.A.at first B.at all C.at large D.at times

33.A.subjected B.left C.drawn D.exposed

34.A.ineffective B.incompetent C.inefficient D.insufficient

35.A.introduce B.summon C.trigger D.create

36.A.still B.also C.otherwise D.nevertheless

37.A.sure B.sick C.aware D.tired

38.A.tolerate B.repel C.neglect D.notice

39.A.available B.reliable C.identifiable D.suitable

40.A.similar to B.such as C.along with D.aside from

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