文档介绍：编辑版word
页脚下载后可删除，如有侵权请告知删除！
编辑版word
2005年考研英语完形填空真题解析
The human nose is an underrated tool. Humans are often thought to be insensitive smellers compared with animals,1this is largely because,2animals, 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 the 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 f