Question

this is one of the books on the subject that

This is one of the books on the subject that ________ ever been written in Chinese． [　　] A． has B． are C． have D． is

Answer 1

答案：C 解析： 先行词为books，that是关系词，引导一个定语从句。再从“ever”(曾经)的意思来看，应该用完成时态。