题目

As we know, the paper is _______ wood. A . made of B . made from C . made up of D . made in 答案：B若有两个电阻R1、R2(R2＞R1)，设串联后的总电阻为R串，并联后的总电阻为R并，那么一定有 A.R串＞R2＞R1＞R并         B.R并＞R串＞R2＞R1 C.R串＞R并＞R1＞R2         D.R串＞R并＞R2＞R1