Hedidn’tknowGerman______madeitdifficultforhimtos

He didn’t know German, ______ made it difficult for him to study at a university in Germany.

A. that

B. as

C. which

D. this

正确答案：C
答案为C他不懂德语这使他很难在德国的大学学习非限定性定语从句指代前一句的内容关系代词在句中做主语