Thisrobotissupposedtosavealotoflabor,butitremainsaprobl...

问题详情：

This robot is supposed to save a lot of labor, but it remains a problem if it ______.

A. is B. saves C. does D. has

【回答】

C

【解析】do(es) 是代动词，用来代替上文save a lot of labor。

知识点：动词时态

题型：选择题