seems very hard to reach the top of the mountains.A. ThatB. ThisC. ID. It

问题补充：

seems very hard to reach the top of the mountains.

A. That

B. This

C. I

D. It

答案：

A. That

B. This

C. I

(答案→)D. It

解析：

试题分析: 句意: 爬到山顶似乎很难。it seems +adj+to do做某事似乎很难，固定句型，it做句中的形式主语，真正主语为不定式， 故答案选B.