–Areyousureyouhaveto?It’sbeenverylate.--Idon’tknow

问题详情：

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

-- I don’t know ______ I can do it if not now.

A. where  B. why   C. when   D. how

【回答】

C

知识点：连词

题型：选择题