when the little boy saw her morther___,she couldn't help___

问题描述:

when the little boy saw her morther___,she couldn't help___
A.coming;laughing B.come;to laugh C.comes; laughs D.came; laughing

选A.
see sb doing 看到某人正在做某事
couldn't help doing 忍不住做某事.
当小男孩看到他母亲过来的时候,她忍不住哭了.