You should think twice before having kids. 你要在生孩子前好好考虑考虑。

　　I'm going to think twice before I try this. 我要在开始前好好考虑考虑。

　　There's always something bugging you. Think hard. 总会有一些事情让你烦恼，好好想想。

　　Let me have time to think it over. 让我找个时间好好想想。

　　Think twice before you choose what to study.  在你决定学什么之前，好好考虑考虑。

　　Yeah, you need to get a good education.  恩，你得接受良好的教育。