求英语大神分析一个句子的语法,谢谢!

问题描述:

求英语大神分析一个句子的语法,谢谢!
His father was a teacherwho _______deaf-mutes learn how to speak.
A which was helped
B that was helped
C who helped
D who has helped
选啥?为什么?

你好,为你解答,正确答案为:
C who helped
他父亲过去是一名帮助聋哑人学习如何开口说话的教师.
不明白请及时追问,满意敬请采纳,O(∩_∩)O谢谢就你吧,我也选的C,但是书里是D,所以疑惑了D 是现在完成时。
用一般过去式就可以的,选C没问题。