【题目】Do you know the reason _____students are so lazy.
A. that B. which C. for which D. with which
在线课程【答案】C
【解析】考查定语从句。句意：你知道学生们如此懒惰的原因吗？从句子结构看，本句是含定语从句中，先行词为the reason，而定语从句中students are so lazy.缺少相对应的的原因状语for the reason,所以该空可以填why 或者for which；故选C。