Question

This question is hard to ( )

A.be answered B.answer

为什么选B不选A

Answer 1

英语中有些形容词，如easy,difficult,hard,dangerous等，后面接动词不定式时，动词不定式往往与主语构成动宾关系，同时，它可以借助it来做形式主语。上面这个句子可以换成以下说法：
This question is hard to answer.
=To answer this question is hard.
=It is hard to answer this question.
由此可见，只能选B不选A。
就像这句This river is dangerous to swim in.

Answer 2

你好，很高兴为你解答\(^o^)/~
这里是主动表被动的特殊用法

Answer 3

不知道你是否听过一句话'It is hard to say.'和你的问题是一样的句型结构。这个句子本来的样子是：To anwser this question is hard.为了避免主语过长，句子结构就变成了This question is hard to answer.