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问题 问答题 简答题

动力转向器中的控制阀有哪些形式？工作原理如何？

答案

参考答案：

有滑阀式和转阀式。工作原理简介：阀体沿轴向移动来控制油液流量的转向控制阀，称为滑阀式转向控制阀；阀体绕其轴线转动来控制油液流量的转向控制阀，称为转阀式转向控制阀

听力题

小题1:I can’t i________    （想象）the life without electricity.

小题2:Talking to f________     can improve your foreign language very fast.

小题3:He hurt his leg, now the doctors are o________     on his leg.

小题4:Your dad went to Qingdao on  b________    （做生意）.

小题5:I went to bed too late last night and I’m very s________    now.

小题6: Read the ________     (说明) carefully before taking the medicine.

小题7:I asked her for help, but she ________        (拒绝).

小题8: He did a ________       (完美的) job, we’re proud of her.

小题9:The write decides to ________   (重写) the story because some readers don’t like it.

小题10: Dr Bethune ________ (发明) some medical tools to help save the injured soldiers.
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单项选择题

在SQL的ALTER TABLE语句中，为了增加一个新的字段应该使用短语______。

A) CREAT
B) APPEND
C) COLUMN
D) ADD
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