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问题 单项选择题

《煤矿安全规程》对提升机制动有规定：常用闸和保险闸共同使用一套闸瓦制动时，操纵和控制机构（）。

A、必须分开

B、应合二为一

C、必须随时可用

D、必须装手把

答案

参考答案：A

填空题

阅读下面短文，用括号内所给动词的适当形式填空（必要时可加助动词或情态动词）。

     It was three o'clock. Robert and his friends (1) ______ (play) hide-and-seek (捉迷藏) in a neighbor's

house. The game was very interesting and they (2) ______ (enjoy) it very much. Suddenly Robert had a

good idea. He smiled to himself. This time he found a good place (3) ______ (hide) in. No one could (4)

 ______ (find) him!

      There was an old fridge in the kitchen. The neighbor (5)______ (not use) it for a long time. Robert

opened the door and went in quietly. Of course, he (6) ______ (not find). But he was in great trouble!

His friends forgot him and they all went home. His mother came to (7) ______ (get) him home, but he was

lost. Everyone helped her (8) ______ (look) for Robert. But no one found him.

     The next morning, the neighbors (9)______ (hear) a knock in the kitchen. It (10)______ (seem) to come

from the old fridge. They opened it and found Robert there! He was dead.

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单项选择题

对以沸石为主的酸性功能的催化剂，加氢裂化的反应速度随分子量的增大而（）。

A、下降

B、先下降再升高

C、升高

D、先升高再下降
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