Some also expressed disappointment that Mr.Obama was not scheduled to attend the end of the Copenhagen summit when the toughest negotiations are expected to take place.

VOA: standard.2009.11.26

That has to count as the toughest day, not only in my career, but also in the history of that particular presidency.

那可以算得上是最艰难的一天，不仅在我的职业生涯里，在总统任期的历史中,也是最艰难的一天吧。

普林斯顿公开课 - 国际座谈会课程节选

One of the jobs of a White House Chief of Staff is to settle disputes among cabinet members and offcials, and it's also one of the toughest jobs.

白宫办公厅主任的,工作之一是解决争端,在内阁成员和其他官员间进行调解，这也是最辛苦的工作之一。

普林斯顿公开课 - 国际座谈会课程节选