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, this is largely because, animals, we stand upright. This means that our noses are to perceiving those smells which float through the air, the majority of smells which stick to surfaces. In fact, , we are extremely sensitive to smells, we do not generally realize it. Our noses are capable of human smells even when these are to far below one part in one million.
Strangely, some people find that they can smell one type of flower but not another, others are sensitive to the smells of both flowers. This may be because some people do not have the genes necessary to generate smell receptors in the nose. These receptors are the cells which sense smells and send to the brain. However, it has been found that even people insensitive to a certain smell can suddenly become sensitive to it when to it often enough.
The explanation for insensitivity to smell seems to be that the brain finds it to keep all smell receptors working all the time but can new receptors if necessary. This may explain why we are not usually sensitive to our own smells—we simply do not need to be. We are not of the usual smell of our own house, but we new smells when we visit someone else’s. The brain finds it best to keep smell receptors for unfamiliar and emergency signals the smell of smoke, which might indicate the danger of fire.
哈工大 | 吉林大學 | 東南大學 | 南京大學 | 上海交大 | 同濟大學 | 復旦大學 | 山東大學 | 大連理工 | 蘭州大學 | 重慶大學 | 西工大 | 西安交大 | 電子科大 | 四川大學 | 中科大 | 武漢大學 | 華中科大 | 中南大學 | 湖南大學 | 廈門大學 | 中山大學 | 浙江大學 | 天津大學 | 南開大學 | 中國農大 | 北京航空 | 北京理工 | 北京師范 | 人民大學 | 北京大學 | 清華大學 |