When I was walking across the square,I saw a plane______over my head.A) flies B) fly C) flewWhen I was walking across the square,I saw a plane______over my head.A) flies B) fly C) flew D) flown

问题描述:

When I was walking across the square,I saw a plane______over my head.A) flies B) fly C) flew
When I was walking across the square,I saw a plane______over my head.A) flies B) fly C) flew D) flown

选B。 see sb.\sth. do 或者doing do强调过程,doing强调动作。

选B
这个句子的谓语是saw
一般来说有这样的结构see something do/doing something.
see 后面跟动词原形或ing形式,所以排除掉ACDA选项.