Not only are mothers not paid but also most of their boring or difficult work is unnoticed.

母亲们不仅得不到报酬，而且所干的乏味艰辛的活儿也很少被留意。

《柯林斯英汉双解大词典》

He finished this difficult work by himself.

他自己完成了这项困难的工作。

youdao

On farms and in factories, they help to do difficult work.

在农场、工厂里它们帮助完成困难的工作。

youdao

"You are helping us to build a cleaner, brighter future and a stronger more prosperous economy and my administration and our country will support you in that difficult work,"

VOA: standard.2009.03.23

But I don't think it's actually, more work, or more difficult work.

但我不觉得，其实，功课更多或功课更难。

对于赞助入学的看法 - SpeakingMax英语口语达人

I'm not going to have you work long hours on difficult problems to be submitted and then graded.

我的作业不会让你们花费大量的时间,去钻研很难的问题，然后交上来让我打分。

麻省理工公开课 - 固态化学导论课程节选

The study revealed that difficult work-life conflicts stall many tech women mid-career and force others to sacrifice their personal lives.

FORBES: Women In Tech Make Sacrifices To Succeed

When I want to do the difficult work of original writing, I often work outside my apartment, in a library a few blocks away.

FORBES: Problems With Procrastination?

And then I will let Alan go back to his important and difficult work, and then I will remain to take questions on other subjects.

WHITEHOUSE: Press Briefing