题目

关于人体内激素和神经递质的叙述，正确的是（ ） A．神经递质的化学本质是蛋白质 B．酶可以供应化学反应所需的活化能 C．一般情况下，激素和神经递质发挥作用后即被灭活或降解 D．与激素特异性结合的受体均分布于靶细胞膜上 答案：解：A、神经递质有生物原胺类、氨基酸类、肽类、其它类四类，因此神经递质的化学本质不一定是蛋白质，A错误； B、酶可以降低化学反应的活化能，B错误； C、一般情况下，激素和神经递质发挥作用后即被灭活或降解，C正确； D、性激素与甲状腺激素能进入细胞，与细胞内特定受体结合从而发挥作用　　Language learning begins with listening. Children are greatly different in the amount of listening they do before they start speaking, and later starters are often long listeners. Most children will “obey” spoken instructions some time before they can speak, though the word“obey”is hardly exact as a description of the eager and delighted co- operation（合作） usually shown by the child. Before they can speak, many children will also ask questions by gestures and by making questioning noises.　　Any attempt to study the development from the noises babies make to their first spoken words leads to considerable difficulties. It’s agreed that they enjoy making noises, and that during the first few months one or two noises sort themselves out as particular expression like delight, pain, friendliness and so on. But since these can’t be said to show the baby’s intention to communicate, they can hardly be regarded as early forms of language. It is agreed too, that from about three months they play with sounds for enjoyment, and that by six months they are able to add new words to their store. This self - imitation（自我模仿）leads out to deliberate（有意的）imitation of sounds made or words spoken to them by other people. The problem then arises to the point at which one can say that these imitations can be considered as speech.　　It is a problem we need to get our teeth into. The meaning of a word depends on what a particular person means by it in a particular situation and it is clear that what a child means by a word will. change as he gains more experience of the world. Thus the use, at seven months, of“ mama” as a greeting for his mother cannot be dismissed as a meaningless sound simply because he also uses it at another time for his father, his dog, or anything else he likes. Playful and meaningless imitation of what other people say continues after the child has begun to speak for himself. I doubt, however , whether anything is gained when parents take advantage of his ability in an attempt to teach new words.　　61．Children who start speaking late ________ 　　A. may have problems with their listening　　B. probably do not hear enough language spoken around them　　C. usually pay close attention to what they hear　　D. often take a long time in learning to listen properly　　62．A baby’s first noises are ________ .　　A. an expression of his moods and feelings　　B. an early form of language　　C. an imitation of the speech of adults　　D. a sign that he means to tell you something　　63．The problem of deciding at what point a baby’s imitation can be considered as speech ________ .　　A. is important because words have different meanings for different people　　B. is not especially important because the change takes place gradually　　C. is one that should be ignored（忽略）because children’s use of words is often meaningless　　D. is one that can never be properly understood because the meaning of words changes with age　　64．The speaker implies that ________ .　　A. even after they have learnt to speak, children still enjoy imitation　　B. children who are good at imitating learn new words more quickly　　C. children no longer imitate people after they begin to speak　　D. patents can never hope to teach their children new sounds