Tom sat under a tree chatting with his friends and his teacher stood up in no time.A. se

问题补充：

Tom sat under a tree chatting with his friends and his teacher, stood up in no time.

A. seeing

B. seen

C. saw

D. to see

答案：

(答案→)A. seeing

B. seen

C. saw

D. to see

解析：in no time“立刻，马上”； his teacher空白处填非谓语形式，作时间状语；逻辑主语是Tom，Tom和see是主谓关系，故用主动形式seeing。“（Tom）看到老师时，立刻站了起来。”故选A。