[-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?

分类: 作业答案 • 2021-12-19 11:08:03

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