sb.+ be doing里面的谓语动词是doing还是be,还是be doing?
sb.+ be doing里面的谓语动词是doing还是be,还是be doing?
sb.be doing +adj还是adv
是be doing+adj还是be doing+adv?
是be tired of doing还是be tired doing
是be up to sb to do还是doing?
be always doing 还是always doing
be expert at doing 还是in doing
there be sb doing
be difificult for sb do 还是doing还是to do
非谓语动词问题find sb doing/done 的否定形式是sb be found at doing吗介词是否为AT
is raining heavily be doing 后面跟的是形容词还是副词 be 动词后跟什么 be动词是什么,b
be prepare do 还是be prepare doing