And scientists have been working on this for years and there's been progress, but it's still a very difficult challenge.

科学家们对此已经研究很久了,并取得了进展,但仍有很大挑战

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

I had been working at a public Accounting firm for a couple of years.

我在一家会计事务所已经工作了几年。

为什么是会计学呢？ - SpeakingMax英语口语达人

I also served for the two years before that as the policy director of President Bush's presidential campain, working at the Texas.

在那之前，我做过两年的,布什总统选举的,政策主任，在德州工作。

普林斯顿公开课 - 国际座谈会课程节选

This is something I've working on for many years and this will be it.

这是我多年努力的目标,这将会是。

哈佛公开课 - 幸福课课程节选

So biomedical engineers have been working for many years on how to design replacement parts for joints like the hip: the artificial hip is the most well developed of those.

因此,生物医学工程师花了很多年时间,致力于设计像髋关节这样的关节替代品,尤以人工髋关节的研究最为成熟

耶鲁公开课 - 生物医学工程探索课程节选

In that year, we were early on in terms of diversifying the portfolio -we'd only been working on that program for two years -and even so,the negative return was less than 1%, so it was a modest negative return.

在那一年,我们还处于投资组合多元化的初期,刚刚开始2年,即便如此,股灾时我们的亏损小于1%,这只是一个轻微的亏损

耶鲁公开课 - 金融市场课程节选

So working with her for 3 years,

所以在为她提供帮助的三年里，

与职业发展咨询老师 - SpeakingMax英语口语达人

People have been working with x-rays for about 30 years by this time.

到现在为止,人类和X射线打交道大约30年了。

麻省理工公开课 - 固态化学导论课程节选

This is something we've been working for many, many years."

这是我们多年来努力的目标“

哈佛公开课 - 幸福课课程节选