we were not surprised at__,for he had worked so hard.

问题描述:

we were not surprised at__,for he had worked so hard.
a.what has he achieved
b.that what has he achieved
c.what he had achieved
d.what has he achieved
为什么选c?知识点是什么?
介词后面除了可以接what外还可以界什么?

很明显这是由what引导的从句,而what 后面的部分用正常语序