Question

英语疑难问题

An even harder situation is to be on the platform in good time for a train and still to see it go off without you.
不太了解be to do 的用法，

Answer 1

1. be to do表示将来时间。如：I am to leave tomorrow.
2. be + to do(to do 充当表语，解释主语内容。这时，常可以与主语位置互换，意思不变）如你的句子可换成：
To be on the platform in good time for a train and still to see it go off without you is an even harder situation.
My idea is to leave tomorrow.
=To leave tomorrow is my idea.

Answer 2

be to do 不定式结构这里作表语，一般指将来。