求解析I wonder ______they have finished their homework.

问题描述:

求解析I wonder ______they have finished their homework.
I wonder ______they have finished their homework.A that B when C where D if

D 是否
翻译:我想知道他们是否已完成作业.
注:A 没有意义; B 什么时候(不能与完成时连用); C 哪里,这三项与句意不符.