The missing boys were last seen near the river. A. playing B. to be playing C.pl

The missing boys were last seen ___ near the river.

A. playing  B. to be playing  C.play   D. to play

试题答案

A

解析:

see 后可接do或doing作宾语补足语，前者表示动作全过程，后者表示动作的进行，此题关键词是 last。