一般设备长期停用的情况，应对该设备进行（）。A、抽真空 B、加盲板氮封 C、打开人孔

小刚在计算41+n时，误将“+”看成了“-”，结果得-12，则41+n的值应为（     ）。

阅读对话，填写适当的单词使对话完整通顺。

A: Hi, Tina! I haven't 1._________ you for a long time. 2._________ have you gone?

B: Oh, I've been to Australia 3._________ vacation. I had a great 4.________ there.

A: That's great! I hope one day I will go there 5._________.

B: What have you been 6.________ these days?

A: I've been 7._________ for a job. I like to travel so I want to be a 8.________ attendant.

B: Have you got the job?

A: I'm afraid not. These days I have been 9._________ English at a language school. 10. _________I have to

   speak English well if I want to get the job.

B: Well, I hope you can improve your English soon.

A: Thank you!

在我国境内提供各种劳务的收入，均应缴纳营业税。( )

发行 * * 票的目的是什么？

下列化合物中（）是碱。

A.氯化钾

B.氢氧化钾

C.硫酸

D.氟利昂