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问题 问答题 简答题

低压法合成氨工艺的缺点？

答案

参考答案：所用催化剂对毒物很敏感、易中毒，使用寿命短，对原料气的精制要求很高。又因操作压力低，氨的反应速率慢、合成率低，反应后气体中氨的分离较困难，流程复杂。

完形填空

Once there lived a rich man   小题1: wanted to do something for the people of his town.   小题2:  first he wanted to find out whether they deserved his help.

In the centre of the main road into the town, he placed   小题3:  very large stone. Then he   小题4: (hide ) behind a tree and waited. Soon an old man came along with his cow.

“Who put this stone in the centre of the road?” said the old man, but he did not try to remove the stone. Instead, with some difficulty he passed around the stone and continued on his way.   小题5:  man came along and did the same thing; then another came ,and another. All of them complained about the stone but not tried to remove  小题6: . Late in the afternoon a young man came along. He saw the stone,   小题7:(say) to himself: “The night   小题8: (be) very dark. Some neighbors will come along later in the dark and will fall against the stone.”                 

Then he began to move the stone. He pushed and pulled with all his   小题9:  (strong) to move it. How great was his surprise at last!   小题10:  the stone, he found a bag of money.
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选择题

He is _______ clever boy that he can solve _____ many difficult problems.

A．so a, so

B．such a, so

C．such, such

D．so, so
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