哪些因素影响热裂解华反应的反应速度？

下列物质中属于纯净物的是     [ ]

A．糖水    

B．牛奶    

C．干冰    

D．啤酒

将现金送存银行，会计人员应填制的记账凭证是( )。

A．现金付款凭证
B．转账凭证
C．银行收款凭证
D．银行收款凭证和现金付款凭证

There was great interest when a big hole mysteriously appeared in the middle of a field. Engineers were called in to explain how it had got there. They offered various explanations but were not at all sure how the hole had been caused, it was thought that a large bomb which came suddenly exploded, but it was not possible to prove this. A simple, but highly improbable explanation was offered by a man who declares to know well about “flying saucers”; the strange objects which are round in shape and are said to visit the earth from outer space. The man’s explanation may have been nonsense (胡说八道), but at least it was imaginative. At any rate, it was far more interesting than the one given by the army.

After examining the ground carefully the man declared to have seen special marks on the soil quite near the hole, these, he said, could only have been caused by a flying saucer. Moreover the leaves on some bushes nearby had turned yellow because of a strange hot gas which had come from the saucer just before it landed. Even a small tree some way off appeared to have been burnt slightly. A small piece of metal found in the hole itself gave further proof that a strange object had been there. According to the man, it was quite clear that people from another world had been going around the earth trying to pick up information, when something had gone wrong. Because of this they had been forced to land in a field so that the damage could be repaired. The hole had been caused when the saucer struck the earth, while the strange marks nearby were made when it took off again. This, said the man, was the simplest explanation of how the hole had appeared. Judging from the interest the public took in the matter, there must be quite a few people who secretly believe or hope that this simple explanation is the true one.

小题1:What aroused public interest?

A．A mysterious hole in a field.

B．Various explanations offered by experts.

C．A simple explanation given by a man.

D．The shape of the flying saucers.小题2:The author thought the man’s explanation was________. 

A．boring but imaginative

B．reasonable and interesting

C．meaningless but interesting

D．mysterious and unbelievable小题3:The man found a lot of proofs except ____. 

A．special marks on soil near the hole

B．yellow leaves on some bushes nearby

C．a small piece of meal in the hole

D．the remains of the flying saucer小题4:It’s said the outer-space people were circling the earth _______.

A．to repair their saucer

B．to strike the earth

C．to. collect information

D．to make strange marks

当汽车在行驶中遇雨雾天气视线不良时，应（）。

活鱼运输要选择高温热天最适宜。