I had to be really persistent and it was very hard work.

我必须非常坚持，这是非常艰难的工作。

youdao

Coping with three babies is very hard work.

照顾3个小宝宝是件很累人的活儿。

《柯林斯英汉双解大词典》

Being a good manager takes very hard work, attention to detail, and organizational discipline.

作为一个优秀的经理承担了非常艰苦的工作，要关注细节、要留意组织纪律。

youdao

Growing cacao is very hard work for farmers.

VOA: special.2010.02.17

You don't have to work very hard to figure out what these different facial expressions mean.

你不必努力地去学习,去辨析不同面部表情的含义。

耶鲁公开课 - 心理学导论课程节选

Or perhaps, you could set a goal to lose weight and you could work very hard.

又或者，你制定了一个减肥的目标，你为此而努力坚持着。

I'm frustrated 课堂 - SpeakingMax英语口语达人

They do very hard work under very stressful circumstances, and almost invariably do an outstanding job.

WHITEHOUSE: President Obama and President Santos Hold a Press Conference | The White House

"I believe in two or three days of very hard work we could have a balanced budget agreement, " he said.

CNN: Budget impasse continues amid mix of pessimism and hope

We've had a good run of races, today's going to be very hard work for Ralf and for his very energetic team-mate Juan Pablo Montoya who was on the fourth row of the grid.

BBC: Breakfast with Frost