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问题 单项选择题

将燕麦胚芽鞘尖端置于琼脂块上并单侧光照射（A.B琼脂块间以玻璃片隔开）一段时间。将A.B琼脂块放在去掉尖端的胚芽鞘上：①遮光；②匀速旋转；③单侧光照。其生长情况依次为（）

A.向B侧弯曲、直立生长、向A侧弯曲

B.向B侧弯曲、向B侧弯曲、向B侧弯曲

C.向A侧弯曲、向A侧弯曲、向A侧弯曲

D.向A侧弯曲、直立生长、向B侧弯曲

答案

参考答案：C

解析：单侧光刺激，导致生长素分布不均，被光侧多向光侧少，因而琼脂块中的生长素含量B大于A。浓度大促进作用强，浓度小促进作用弱，所以①向左（A侧）弯曲生长；②向A侧弯曲生长；③向A侧弯曲生长，原因是光对琼脂块中生长素的分布无影响。考点：本题考查激素的作用，意在考知识的理解应用及分析能力。

单项选择题

In the United States and in many other countries around the world, there are four main ways for people to be (91) about developments in the news: newspapers, magazines, and radio or television news broadcasts. A person may use one, or all, of these (92) for information. Each source is useful in its (93) way. Newspapers and magazines can give much information about a particular event. They may (94) some history of the event, some of its (95) , some of its effects, or perhaps give an (96) or point of view on a particular development. Radio and television can help a person to be well informed about what is happening each day. It is also (97) to listen to radio or watch TV (98) do something else at the same time. Many people can listen to the news on their car radio while driving (99) . For the student of English as a foreign language, an English language newspaper may be the most helpful news source that will also (100) you practice in reading English.
Most daily English language newspapers are not very hard to find. They are interesting and helpful in many (101) . In some of them, you may be able to find news about your (102) country. You will find news and information about important national and international political (103) . (104) what you are interested in, you can probably find something in the newspaper about it. A(n) (105) in the newspaper may help you solve a problem. Other stories may be about good movies, concerts, or TV shows.
Usually, an English language newspaper has several (106) or parts. Each part of the newspaper (107) stories about different kinds of news. Some sections have a lot of advertisements which may be helpful if you want to save money. By reading the advertisements, you may find something you want (108) sale. Or you may find that two stories are advertising the (109) thing, but at one store the price is lower. Other sections may have (110) advertisements or have only a specific type of advertisement to interest the people.

A．means

B．sides

C．ways

D．kinds
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单项选择题

动机强度和学习效率的关系是( )

A．正比关系

B．U型曲线关系

C．倒U型曲线关系

D．反比关系
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