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问题 多项选择题

关于抗原抗体结合力，下列正确的是（）

A.疏水作用力对维系抗原抗体的结合作用最大

B.氢键结合力是供氢体上的氢原子与受氢体上氧原子间的作用力

C.抗原抗体之间不形成牢固的共价键

D.范登华力的能量最小

E.静电引力的大小与两个电荷间的距离成反比

答案

参考答案：A, C, D

完形填空

基础训练篇（17）

In order to know a foreign language thoroughly, four things are necessary. Firstly, we must understand the language when we hear    1.           spoken. Secondly, we must be able to speak it ourselves correctly with confidence and without hesitation.    2.                , we must be able to read the language, and fourthly, we must be able to write it. We must be able to make sentences that are grammatically correct.

There is no easy way to success   3.            language learning.          4.                   good memory is a great help, but it is not enough only    5.                   (memorize) rules from a grammar book. It is not much use learning by heart long lists of words and   6.             meanings, studying the dictionary and so on. We must learn by using the language. 7.               we are satisfied with only a few rules we have memorized, we are not really learning the language. “Learn through use” is a good piece of   8.            (advise) for those   9.           are studying a new language. Practice is important. We must practise speaking and   10.            (write) the language whenever we can.
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选择题

液化石油气作为燃料，已普遍进入城市家庭，它是含有下列物质的混合物，在常压下，这些物质的沸点如下表所示：

物质名称乙烷丙烷丁烷戊烷己烷
沸点/℃-88.6-42.2-0.536.169.2
在常温下使用至无气体放出时，钢瓶中常剩余一些液态物质，这些物质最有可能是（　　）

A．乙烷、丙烷和丁烷

B．乙烷和丙烷

C．只有乙烷

D．戊烷和己烷
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