特殊疑问词引导的宾语从句,动词用第几人称?

题目

特殊疑问词引导的宾语从句,动词用第几人称?
用适当的形式填空：1.He taught himself how ___(swim) two years ago.
2.Who ___(teach) you to piay the violin last year.

答案

1.He taught himself how _to swim__(swim) two years ago.
2.Who _taught__(teach) you to play the violin last year?