企源知识库

You must tackle the hardest problem _____ is confronting your business because you need to know whether or not you can go through it.
A、that
B、with which
C、which
D、why
【正确答案】：A
【题目解析】：先行词有最高级形容词修饰的时候，关系从句的引导词用that。因此，A为正确答案。