It's pretty hard to explain.

这事很难解释清楚。

《牛津词典》

It can be pretty hard work, but it pays really well.

这份工作可能很辛苦，但报酬很好。

youdao

You would have to be pretty hard-hearted not to feel something for him.

你必须是非常铁石心肠才能对他没有一点同情。

《柯林斯英汉双解大词典》

I don't know if you're aware of this, but these honorary degrees are apparently pretty hard to come by.

VOA: standard.2009.05.17

It's a problem set where we've worked pretty hard to write some problems that we think will provide you with a good learning experience.

我们为了写出这个问题集,让大家好好学习下课没少侠功夫,你们应该通过材料来学习学习它。

麻省理工公开课 - 计算机科学及编程导论课程节选

There's been a lot of work done on these over the years, but in fact, it's pretty hard to invent a good hash function. So my advice to you is, if you want to use something was a hash, go to a library. Look up a good hash function.

已经做过了很多的尝试和努力,但是事实是，很难发明出一个好的哈希函数,所以我给你们的建议是,如果你们想使用哈希功能,到函数库中查找一个好的哈希函数。

麻省理工公开课 - 计算机科学及编程导论课程节选

MacFARLAND: Well, he's a friend of mine and his loss hit me pretty hard.

NPR: Murdered Sheik Was Fearless Fighter, Colonel Says

So I think we are working pretty hard to make sure that they could do so.

BBC: News | NEWSNIGHT | Smallpox interview transcript

But when it comes to Jobs, the stats are getting pretty hard to decipher.

FORBES: The Medical Mismeasure of Steve Jobs