一、真題文章（2005年完型）
The human nose is an underrated tool. Humans are often thought to be insensitive smellers compared with animals， while this is largely because， unlike animals ，we stand upright. This means that our noses are limited to perceiving those smells which float through the air， missing the majority of smells which stick to surfaces. In fact， instead ， we are extremely sensitive to smells， even if we do not generally realize it. Our noses are capable of detecting human smells even when these are diluted to far below one part in one million.
Strangely， some people find that they can smell one type of flower but not another， whereas others are sensitive to the smells of both flowers. This may be because some people do not have the genes necessary to generate particular smell receptors in the nose. These receptors are the cells which sense smells and send messages to the brain. However， it has been found that even people insensitive to a certain smell at first can suddenly become sensitive to it when exposed to it often enough.
The explanation for insensitivity to smell seems to be that brain finds it inefficient to keep all smell receptors working all the time but can trigger new receptors if necessary. This may also explain why we are not usually sensitive to our own smells ——we simply do not need to be. We are not aware of the usual smell of our own house but we notice new smells when we visit someone else's. The brain finds it best to keep smell receptors available for unfamiliar and emergency signals such as the smell of smoke， which might indicate the danger of fire.
二、考研核心詞匯
underrate vt. 低估 ， 看輕
[例] We underrated his powers as a speaker . 我們低估了他的演說才能。
[同義] belittle， minimize ， underestimate
[反義] overrate vt. 對估價過高
upright adj. 垂直的， 豎式的， 正直的， 誠實的， 合乎正道的
adv. 筆直 ， 豎立著 n. 垂直， 豎立
[例] an upright man 正直的人
[同義] erect， honorable， law-abiding， moral， reputable， respectable， standing
[反義] dishonest adj. 不誠實的
[派生] uprightly adv. 筆直地， 正直地
perceive /vt. 察覺 v. 感知， 感到 ， 認識到
[例] I perceived that I could not make her change her mind.
我發(fā)覺我不能使她改變她的主意。
[同義] detect ，distinguish， experience， feel ，make out ，observe， recognize， sense
[派生] perceivable / adj. 可知覺的
surface n. 表面， 外表， 水面 adj. 表面的， 膚淺的
[例] The truth began to surface. 真相開始露出來。
[同義] exterior， face ， outside
[反義] interior adj. 內部的， 內的 n. 內部
detect vt. 察覺， 發(fā)覺， 偵查， 探測 v. 發(fā)現(xiàn)
[例] The dentist could detect no sign of decay in her teeth.
牙醫(yī)在她的牙齒上找不到蛀蝕的跡象。
[同義] catch ，discover ，perceive ，recognize
[反義] conceal vt. 隱藏， 隱蔽， 隱瞞 v. 隱蔽
[派生] detection n. 察覺， 發(fā)覺， 偵查， 探測， 發(fā)現(xiàn)
dilute v. 沖 淡， 變淡， 變弱， 稀釋 adj. 淡的， 弱的， 稀釋的
[例] The nurse diluted the drug with saline water.
護士用生理鹽水把藥加以稀釋。
[同義] cut， reduce， thin ，weaken
[派生] diluted / adj. 無力的 沖淡的
dilution di5l- / n. 稀釋， 稀釋法，沖淡物
receptor n. 接受器 ， 感受器， 受體
[例] receptor of radiation 輻射探測器
expose vt. 使暴露， 受到， 使曝光 v. 揭露
[例] The crime of the corrupt officials must be exposed without any reserve.
對貪官污吏的罪行一定要毫無保留地予以揭發(fā)。
[同義] disclose， display ，open ，reveal ，show， uncover ，unmask
[反義] conceal vt. 隱藏， 隱蔽， 隱瞞 v. 隱蔽
[派生] exposal / n. 曝光， 顯露
[固定搭配] expose……to 使……受到， 使……朝向 ……；使 ……接觸 ……
trigger vt. 引發(fā)， 引起， 觸發(fā) n. 板機
[例] The odor of food may be a trigger for man's appetite.
食物的香味能引起人的食欲。
[同義] begin， fire ，kindle， start ，touch off
emergency n. 緊急情況 ， 突然事件， 非常時刻， 緊急事件
[例] In an emergency， telephone the police.
出現(xiàn)緊急情況時，請給警察打電話。
[同義] crisis ， crucial ， period， pinch
[派生] emergent adj. 緊急的， 浮現(xiàn)的， 突然出現(xiàn) 的， 自然發(fā)生的
The human nose is an underrated tool. Humans are often thought to be insensitive smellers compared with animals， while this is largely because， unlike animals ，we stand upright. This means that our noses are limited to perceiving those smells which float through the air， missing the majority of smells which stick to surfaces. In fact， instead ， we are extremely sensitive to smells， even if we do not generally realize it. Our noses are capable of detecting human smells even when these are diluted to far below one part in one million.
Strangely， some people find that they can smell one type of flower but not another， whereas others are sensitive to the smells of both flowers. This may be because some people do not have the genes necessary to generate particular smell receptors in the nose. These receptors are the cells which sense smells and send messages to the brain. However， it has been found that even people insensitive to a certain smell at first can suddenly become sensitive to it when exposed to it often enough.
The explanation for insensitivity to smell seems to be that brain finds it inefficient to keep all smell receptors working all the time but can trigger new receptors if necessary. This may also explain why we are not usually sensitive to our own smells ——we simply do not need to be. We are not aware of the usual smell of our own house but we notice new smells when we visit someone else's. The brain finds it best to keep smell receptors available for unfamiliar and emergency signals such as the smell of smoke， which might indicate the danger of fire.
二、考研核心詞匯
underrate vt. 低估 ， 看輕
[例] We underrated his powers as a speaker . 我們低估了他的演說才能。
[同義] belittle， minimize ， underestimate
[反義] overrate vt. 對估價過高
upright adj. 垂直的， 豎式的， 正直的， 誠實的， 合乎正道的
adv. 筆直 ， 豎立著 n. 垂直， 豎立
[例] an upright man 正直的人
[同義] erect， honorable， law-abiding， moral， reputable， respectable， standing
[反義] dishonest adj. 不誠實的
[派生] uprightly adv. 筆直地， 正直地
perceive /vt. 察覺 v. 感知， 感到 ， 認識到
[例] I perceived that I could not make her change her mind.
我發(fā)覺我不能使她改變她的主意。
[同義] detect ，distinguish， experience， feel ，make out ，observe， recognize， sense
[派生] perceivable / adj. 可知覺的
surface n. 表面， 外表， 水面 adj. 表面的， 膚淺的
[例] The truth began to surface. 真相開始露出來。
[同義] exterior， face ， outside
[反義] interior adj. 內部的， 內的 n. 內部
detect vt. 察覺， 發(fā)覺， 偵查， 探測 v. 發(fā)現(xiàn)
[例] The dentist could detect no sign of decay in her teeth.
牙醫(yī)在她的牙齒上找不到蛀蝕的跡象。
[同義] catch ，discover ，perceive ，recognize
[反義] conceal vt. 隱藏， 隱蔽， 隱瞞 v. 隱蔽
[派生] detection n. 察覺， 發(fā)覺， 偵查， 探測， 發(fā)現(xiàn)
dilute v. 沖 淡， 變淡， 變弱， 稀釋 adj. 淡的， 弱的， 稀釋的
[例] The nurse diluted the drug with saline water.
護士用生理鹽水把藥加以稀釋。
[同義] cut， reduce， thin ，weaken
[派生] diluted / adj. 無力的 沖淡的
dilution di5l- / n. 稀釋， 稀釋法，沖淡物
receptor n. 接受器 ， 感受器， 受體
[例] receptor of radiation 輻射探測器
expose vt. 使暴露， 受到， 使曝光 v. 揭露
[例] The crime of the corrupt officials must be exposed without any reserve.
對貪官污吏的罪行一定要毫無保留地予以揭發(fā)。
[同義] disclose， display ，open ，reveal ，show， uncover ，unmask
[反義] conceal vt. 隱藏， 隱蔽， 隱瞞 v. 隱蔽
[派生] exposal / n. 曝光， 顯露
[固定搭配] expose……to 使……受到， 使……朝向 ……；使 ……接觸 ……
trigger vt. 引發(fā)， 引起， 觸發(fā) n. 板機
[例] The odor of food may be a trigger for man's appetite.
食物的香味能引起人的食欲。
[同義] begin， fire ，kindle， start ，touch off
emergency n. 緊急情況 ， 突然事件， 非常時刻， 緊急事件
[例] In an emergency， telephone the police.
出現(xiàn)緊急情況時，請給警察打電話。
[同義] crisis ， crucial ， period， pinch
[派生] emergent adj. 緊急的， 浮現(xiàn)的， 突然出現(xiàn) 的， 自然發(fā)生的