Welcome to English in a Minute.
Sometimes, American English is confusing and hard to understand, like: burn the midnight oil.
有时候，美语有些糊里糊涂的，很费解，就比如：burn the midnight oil（挑灯夜战）。
Everybody knows Americans burn a lot of oil, but is there a special oil that they burn in the middle of the night?
I have big exam tomorrow.
Are you prepared?
No, not at all! I have to burn the midnight oil, I need to do well on this exam.
没有，没怎么准备。我今天不得不挑灯夜战（burn the midnight oil），我需要取得一个不错的成绩。
Americans are not burning a special oil reserved for the middle of the night, they are just staying up very late.
This actually makes sense if you think of a candle, or a lantern, and you have a lot of work to do, that may take you all night.
This is a phrase everybody will understand, and you can use this phrase when you have a lot of work to do, and not that much time to do it in.
And that's English in a Minute.