实验室常用变阻器有______和______两种，它们都是通过改变连入电路中__

一 You could get a tutor to help with your English.

— _______ But my parents don't have much money. [ ]

A．It doesn't matter.

B．You've welcome.

C．That's a good idea.

D．I don't think so.

(2011·北京高考)—Where are the children? The dinner's going to be completely ruined.

—I wish they______always late.

A．weren't

B．hadn't been

C．wouldn't be

D．wouldn't have been

以证据的来源不同，可以把证据分为（）和传来证据。

一切为了群众，就是要把全心全意为人民服务的思想与履行自己的职责统一起来，一方面有效地打击违法犯罪，另一方面保障人民群众的权利和利益．( )

在钻井困难地区如城市、工业区等经常使用的震源是炸药震源。