Did Peter fix the computer himself?

问题描述:

Did Peter fix the computer himself?
-He _______ ,because he doesn't know much about computers.
A.has it fixed B.had fixed it
C.had it fixed D.fixed it
选C为什么不选A

问句中是did 过去时
答句要过去时
短语是have sth done (某事让别人去做)
不是完成时had it fixed 这个是过去时,不是过去完成时!!!!???