lead up to:作為…的準備
These circumstances will lead up to war.
這些事件會導致戰爭。
However, as many of us know, the lead up to the Beijing Olympics has not been as peaceful as one would like.
但是，我想大家都有耳聞目睹，這次北京奧運的前奏沒有我們預期的那么和平。

in retrospect: 回顧往事
In retrospect, at that time AIDS was not sufficiently on the radar of the Department of Peacekeeping Operations.
回顧過去，當時艾滋病并未得到維持和平行動部的充分注意。
In retrospect, the biggest blunders often seem inexplicable.
回首過去，我們發現，最嚴重的錯誤往往也是最不可思議的錯誤。

bummed out: 不高興，煩惱
I had an argument with my boyfriend yesterday. I'm bummed out.
昨天我和男朋友吵架了，我很沮喪。
It's like an ongoing state of being totally bummed out.
它是一種持續的毫無興致的狀態。

the lesser of the two evils: 兩害之較輕者
People voted for him as the lesser of two evils.
人們投票支持他只不過是兩害相權取其輕罷了。