干燥进行的必要条件是物质表面的水气的压强，必须（）干燥介质中水气的分压。A、＜ B、

两原子的实际质量比等于他们的相对原子质量比______．（判断对错）

根据对话内容，补全对话，每空一词。

Mr. Shaw: Good afternoon. What can I do for you?

Mrs. Clark: I'd like to    1    a washing machine.

Mr. Shaw: This is the newest washing machine.

Mrs. Clark: Is it    2    in Sweden?

Mr. Shaw: No, it's made in Germany.

Mrs. Clark: Please show me how to    3    it.

Mr. Shaw: Sure, here are some sheets and shirts; you    4    them in the machine.

                You    5    the door and    6    this button.

Mrs. Clark: Oh, but the machine shouldn't    7    like that. It's shaking.

Mr. Shaw: The ground is not so flat, madam.

Mrs. Clark: It makes so much noise.

Mr. Shaw: Washing machines always make noise.

Mrs. Clark: Well, let me think about it. Thank you.

1._______ 2._______ 3._______ 4._______ 5._______ 6._______ 7._______

以下列哪个物体作为参照物，教室里的讲台是处于静止状态（　　）

A．教室里的黑板

B．教室地面上滚动的篮球

C．学校外面行驶的汽车

D．教学楼内上升的电梯

煤矿井下掘进机必须前有照明后有尾灯，非操作侧有()。

A.铭牌 

B.护栏 

C.急停按钮

中关村所在的______形地带，习称 “电子一条街”外国人称它为推动中国现代化的______。P51