问题 不定项选择题

下列各图所表示的实验操作,哪一项可以将食盐水中的食盐结晶出来[ ]

A.

B.

C.

D.

答案

答案:C

题目分析:

选项A、是加水稀释的过程与析出晶体无关,故A错误。
选项B、过滤是分离固体与液体的方法,与晶体析出无关,故B错误。
选项C、蒸发是减少溶剂的过程,能使溶液析出溶质,故C正确。
选项D、增加溶液的量与析出溶质无关,故D错误。
故选:C

单项选择题
单项选择题

Generally speaking, a British is widely regarded as a quiet, shy and conservative person who is (1) only among those with whom he is acquainted. When a stranger is at present, he often seems nervous, (2) embarrassed. You have to take a commuter train any morning or evening to (3) the truth of this. Serious-looking businessmen and women sit reading their newspapers or dozing in a corner; hardly anybody talks, since to do so would be considered quite offensive. (4) , there is an unwritten but clearly understood code of behavior which, (5) broken, makes the offender immediately the object of (6) .

It has been known as a fact that a British has a (7) for the discussion of their weather and that, if given a chance, he will talk about it (8) . Some people argue that it is because the British weather seldom (9) forecast and hence becomes a source of interest and (10) to everyone. This may be so. (11) a British cannot have much (12) in the weathermen, who, after promising fine, sunny weather for the following day, are often proved wrong (13) a cloud over the Atlantic brings rainy weather to all districts! The man in the street seems to be as accurate — or as inaccurate — as the weathermen in his (14) .

Foreigners may be surprised at the number of references (15) weather that the British make to each other in the course of a single day. Very often conversational greetings are (16) by comments on the weather. "Nice day, isn’t it" "Beautiful!" may well be heard instead of "Good morning, how are you" (17) the foreigner may consider this exaggerated and comic, it is worthwhile pointing out that it could be used to his advantage. (18) he wants to start a conversation with a British but is (19) to know where to begin, he could do well to mention the state of the weather. It is a safe subject which will (20) an answer from even the most reserved of the British.

11()

A.Still

B.Also

C.Certainly

D.Fundamentally