下面文段中画横线的词语使用不正确的一项是（ ）《红楼梦》从问世起就一直谜团不断。它究竟表达了怎样的主题它为什么会有众多的版本高鹗所续写的后四十回是狗尾续貂还是锦上添花这些话题引发了世人旷日持久的争论，学术界也众说纷纭，莫衷一是。而二百多年后的今天，我们惊异地发现，尽管我们破解了许多红学难题，但困惑与疑问依然纷至沓来，我们对它依然讳莫如深。

I’d try even if I may fail ___ __ sit there worrying in time of trouble.

He is very ______ and well-qualified, so he should reach the top of his profession.

Why did you cancel your trip to the New York? —We were just about to leave_______ it started to snow

It is difficult me _______ English well. But I’ll study harder.