2012年自考《英语（二）》每日一练（11.16）
单选题
1.This is an important problem _______ too few social scientists have researched.
A.which
B.that
C.into that
D.into which
正确答案： D
答案解析： into which引导的是problem的定语从句。which指代problem，into与research搭配。
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