问题补充:
This big bag is too heavy for the little boy .Who volunteers to help him?
A. carries
B. carrying
C. carried
D. to carry
答案:
A. carries
B. carrying
C. carried
(答案→)D. to carry
解析:句意:携带这个大包裹对于这个小男孩来说太重。谁自愿帮助他一下?句式It is adj for sb to do sth中不定式做补足语,表示具体的动作。故选D。