【俚語】

Use your noodle！
Use your brain!
用腦子想一想！

【例句】
He gave you $10,000? Use your noodle！It’s not that easy!
他給你一萬美金？用腦子想想！沒那么簡單！

Think twice 再三考慮

【例句】
You'd better think twice if you’re gonna invest so much money in a project you know so little about.
投這么多錢到一個你不太了解的項目里，你最好還是三思啊。

Think long and hard 認真思考

【例句】
I’ve been thinking long and hard about going abroad. I just can’t make a decision.
我最近一直都在認真思考要不要出國。我就是沒法做決定。

Think sth. over
作決定前認真考慮

【例句】
I don’t think he’s the one for you. You need to think it over.
我感覺他不適合你。你需要認真考慮一下。

Have another think coming
想錯了

【例句】
If you think you can walk in here and just demand a raise, you've got another think coming.
如果你感覺就這樣走進來，要求加薪的話，那你就想錯了。