You better be careful, or you know where you'll go.

你最好小心点儿，不然你知道你会到哪里去。

youdao

But when you do a dimensional analysis, you better be careful.

但我们必须谨慎地进行，量纲分析。

youdao

You'd better think carefully before you speak, and be careful when you do your work.

你说话前要三思，工作时要细心。

youdao

You'd better be careful.

你最好小心点。

I'd better 实战 - SpeakingMax英语口语达人

He said, you better be careful around them.

NPR: Raising Dogs, Fighting Dogs

Very nice, Sammy, but you better be careful playing with fire here, as we've found it pretty easy to death grip Galaxy S phones like the Captivate into losing a fair bit of signal.

ENGADGET: Samsung dispatching free Galaxy S handsets to iPhone 4 whiners on Twitter?

You better be careful.

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