are you sure you have to?it is been very late.i dont know_____.i can do it if not now.选项：where, why, when, how.
问题描述：
are you sure you have to?it is been very late.
i dont know_____.i can do it if not now.
选项：where, why, when, how.
答
i don't know when .i can do it if not now.
答
why
答
when,如果现在不能做,我不知道我什么时候能做
答
when
答
选when [如果现在不做我不知道何时才能做.]
答
when 吧，就只有这个翻译的通