[-C28] -They haven't finished all the work up to now.-They ______ .
问题描述：
[-C28] -They haven't finished all the work up to now.-They ______ .
A.should
B.ought to
C.are supposed to
D.are supposed to have
为什么选D不选B?
答
这是省略的一种
省略中 有 be 动词的 保留到be ,有不定式的 保留到不定式to ,有完成时时态标志have / has的 要保留到 have / has.
所以要选D