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问题 选择题

除去混在NO2气体中的少量NH3，可选用的试剂为（   ）

A．浓H2SO4

B．NaOH溶液

C．稀H2SO4

D．水

答案

答案：A

由于NO2易与水反应生成HNO3，故不能用NaOH溶液、稀H2SO4及水吸收氨气，只能选用浓H2SO4。

单项选择题 B型题

神经细胞动作电位的复极相，K+外流至膜外，又暂时阻碍K进一步外流，结果形成（）

A.锋电位

B.阈电位

C.负后电位

D.局部电位

E.正后电位
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单项选择题

In every cultivated language there are two great classes of words which, taken together, comprises the whole vocabulary. First, there are those words (1) which we become acquainted in daily conversation, which we (2) , that is to say, from the (3) of our own family and from our familiar associates, and (4) we should know and use (5) we could not read or write. They (6) the common things of life, and are the stock in trade of all who (7) the language. Such words may be called "popular", since they belong to the people (8) and are not the exclusive (9) of a limited class.

On the other hand, our language (10) a multitude of words which are comparatively (11) used in ordinary conversation. Their meanings are known to every educated person, but there is little (12) to use them at home or in the market-place. Our (13) acquaintance with them comes not from our mother’s (14) or from the talk of our school-mates, (15) from books that we read, lectures that we (16) , or the more (17) conversation of highly educated speakers who are discussing some particular (18) in a style appropriately elevated above the habitual (19) of everyday life. Such words are called "learned", and the (20) between them and the "popular" words is of great importance to a right understanding of linguistic process.

14（）

A.tips

B.mouth

C.lips

D.tongue
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