The situation became harder and harder.

形势越来越严峻。

I will study science harder and harder.

我会越来越努力学习科学。

It's harder and harder to be a student now.

现在的学生越来越苦了。

But she look at me and cry harder and harder.

但是她看着我并哭得越来越厉害。

A drum in the desert, harder and harder to hear.

沙漠里的鼓声，越来越依稀难辨

Knowing this, they’ll study harder and harder.

知道了这点，他们会越来越努力学习。

While(he was)doing so, he felt harder and harder.

在做的过程中，他感觉到越来越难。

It was getting harder and harder to see anything at dusk.

但在傍晚时刻，能见度越来越低。

It was raining harder and harder, so we had to stay at home.

雨下得越来越大，所以我们只得呆在家里。

Cook: It’s harder and harder to reach voters than it used to be.

库克：与过去相比，接触全体选民变得越来越难。