69.– Are you sure you have to?It’s been very late.

题目

69.– Are you sure you have to?It’s been very late.
　　-- I don’t know ______ I can do it if not now.
　　A.whereB.whyC.whenD.how

答案

c吧 句子成分完整 主要是根据句意选.if not now 如果不是现在的话 所以前面强调时间 应该是c