It is wise of you to          well-trained workers            untrained ones in the assembly line.

[     ]

A. substitute; for

B. substitute; with

C. replace; by

D. replace; with

答案

A

考点名称：动词

动词的定义：

表示动作中状态的词叫做动词。根据其在句中的功能，动词可分为行为动词、系动词、助动词和情态动词四类，有些动词是兼类词。

例如：We have lunch at 12. (have是行为动词)

We have been to NewYork. (have是助动词)

I am hungry. (am是系动词)

You need not have waited for me. (need是情态动词)

The door needs painting. (need是兼类词)