Ihavetwogrammars,

问题详情：

I have two grammars, ______are of great use.

A. all of which       B. either of which    C. both of that      D. both of which

【回答】

 D. 主句中的two表明不能选A.从句中的are表明不能选B. both of which用来引导非限制*定语从句.

知识点：定语从句

题型：选择题