【正文】 to the synaptic cleft . For the nerve signal to continue, acetylcholine must diffuse to another nearby neuron or muscle cell, where it will bind and activate a receptor protein. There are two main types of cholinergic receptors, nicotinic and muscarinic. Nicotinic receptors are located at synapses between two neurons and at synapses between neurons and skeletal muscle cells. Upon activation a nicotinic receptor acts as a channel for the movement of ions into and out of the neuron, directly resulting in depolarization of the neuron. Muscarinic receptors, located at the synapses of nerves with smooth or cardiac muscle, trigger a chain of chemical events referred to as signal transduction. For a cholinergic neuron to receive another impulse, acetylcholine must be released from the receptor to which it has bound. This will only happen if the concentration of acetylcholine in the synaptic cleft is very low. Low synaptic concentrations of acetylcholine can be maintained via a hydrolysis reaction catalyzed by the enzyme acetylcholinesterase. This enzyme hydrolyzes acetylcholine into acetic acid and choline. If acetylcholinesterase activity is inhibited, the synaptic concentration of acetylcholine will remain higher than normal. If this inhibition is irreversible, as in the case of exposure to many nerve gases and some pesticides, sweating, bronchial constriction, convulsions, paralysis, and possibly death can occur. Although irreversible inhibition is dangerous, beneficial effects may be derived from transient (reversible) inhibition. Drugs that inhibit acetylcholinesterase in a reversible manner have been shown to improve memory in some people with Alzheimer39。 45. 到時見了面咱們把這些日子發(fā)生的事聊一聊，會多開心啊。 My home is far from the city centre. 我家遠離市中心。 This shirt is too small. B： 不，我覺得夠大了。 No, I think it is big enough. 如何點餐： Can I help you, sir? B: Could we have cheese and bread, please? A: Yes. A: How about seeing a film tonight? B: Great. What’s on ? A:The Titanic B: It’s said to be very good. A: Shall we have something to eat after film? B: That’s a good idea. Let’s do it 你對面授課的建議是：希望老師對語法講解更透徹，重點更突出。 He walks towards the windows 他朝窗戶這邊走來 X) F They went down the road. 他們沿著馬路走 Beijing is an hour’s drive from Tianjing. 北京距離天津驅(qū)車一小時的路程 Chengdu is northewest of Chongqing. 成都位于重慶市西 北部 時間段和時間點：從 by/ until (Unit 26)。 英語 I(2)形考冊作業(yè) 3參考 答案 （ 2528頁） 學習記錄卡 3 完成下面的記錄卡 ,一起來把 Unit31 到 Unit35 這五個單元里你學習到的主要語法／功能總結(jié)一下： 被動語態(tài)的用法和構(gòu)成（ Unit32） 把下面三個句子變成被動語態(tài)： Mary cleans the room every day. The room is clean every day by Mary. The laptop was stolen by his neighbor They have contacted the police. The police have been contacted by them. 與現(xiàn)在或?qū)砬闆r相反的虛擬條件句（ Unit33） 根據(jù)你自己的情況，寫一段話，用到 If I …, I would… 句型。s disease. abstract expressionism, movement of abstract painting that emerged in New York City during the mid1940s and attained singular prominence in American art in the following decade。 a circle is circumscribed about a polygon if all the vertices of the polygon lie on the circumference. The length of the circumference C of a circle is equal to π (see pi) times twice the radius distance r, or C=2πr. The area A bounded by a circle is given by A=πr2. Greek geometry left many unsolved problems about circles, including the problem of squaring the circle, ., constructing a square with an area equal to that of a given circle, using only a straight edge and pass。, and surrealism, became more personally expressive. Jackson Pollock39。 定語從句（非限定性和限定性）（ Unit 34／ Unit 35） 把 下面的句子翻譯成漢語： He bought the trousers that I chose for him. 他買了我給他挑選的褲子 。for/ since (Unit 27)中選詞填空。 42. 桑迪穿了條黑色的長絲裙。 I have been to Beijing. prefer 和 rather區(qū)分 I’d prefer to go to the theatre. rent 和 hire區(qū)分 I’m going to rent a flat. Play, do, go 與運動項目搭配時的區(qū)別 I do KungFu every Friday. He likes to play chess in his free time. 他直到 10點才起床。 A: Which of the two books do you like? 兩本書你喜歡哪本？ B: Neither of them, thanks. 兩本都不喜歡，謝謝 Both the Eiffel and the Concorde have facilities. Eiffel和 Concorde 酒店都有收發(fā)電子郵件設(shè)施。 42. 你像你的母親或父親嗎？ 43. 我周五得從房子里搬出來，因為佛朗哥又招了一位房客。 in response to activation of this nerve supply, smooth muscle contracts (notably in the gut), the frequency of heart beat is slowed, and glands secrete. Acetylcholine is also an important transmitter at many sites in the brain at nerveto