It is difficult to convey the sheer complexity of the situation.

很清楚形势究竟有多复杂。

The plan's success was balanced on a knife-edge.

计划能否成功还很。

It was nip and tuck as to which boat would reach port first.

两条船中哪一条先进港都很。

It is a tossup whether we shall get there in time.

我们是否能及时赶到那里还很。

He's a hard nut to crack.

他是个很服的人。

There's no telling what may happen.

很会发什么事。

We should get to London before 7 o’clock, but there’s many a slip ’twixt cup and lip.

我们应能在7点钟以前赶到伦敦，可是事情往往很准。

But only one reminds me of the courage and persistence it takes to stay the course in the Shadowland.

很哪一个对我最重要，然而，仅有一件能提醒我在阴影之地坚持下去所需要的勇气和坚韧不拔精神。

It is hard to say.

很。

With so many reports to mislead one, it is hard to say at whose door the responsibility should be laid.

告多得摸不着头绪, 很责任该由谁负。