单选题
0.5分
The human nose is an underrated tool.Humans are often thought to be insensitive smellers compared wi...
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 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 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.
3选?
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 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.
3选?
参考答案: A
参考解析: 词义辨析
【难度系数】0.395
【解析】 空所在的句子开头用“this means…”,显然这是对上面一句的继续解释,句子说“我们的鼻子 感受到那些浮在空气中的气味,大部分气味依附于地面。”前文已经谈到由于人类的直立而使得人类不如动物敏感,那么直立自然应该能感受到浮在空气中的气味,而感受不到依附于地面的气味,这样人类的嗅觉就是有局限的,因此前面的一个空填入的词应该表示局限于空气中的气味,后面一空填的应该表示没有能感觉到依附于地面的气味,符合这一语义的第一空为limited,后一空为missing,故本题答案为A,下一空答案为C。第一空可能有人选了D,confine表示在大范围的限定,而且数量或这范围是明确的,这里空气中显然是没有明确界限的,故不能选D。而下一空可能有考生错选ignoring,这一词通常表示主观忽略,不能感觉到依附于地面的气味不能说是人的主观愿望,故不能选。