高等继续教育 / 专科英语II
正确率：100%
题型描述: 单选题
We have learned _ _ _ _ _ _ the rocks on the moon are 3,500 million years old.
A. that
B. how
C. which
D. what
We have learned _ _ _ _ _ _ the rocks on the moon are 3,500 million years old.
A. that
B. how
C. which
D. what
参考答案：