double cross 背叛，不誠實，欺騙他人的行為。

Double cross - the way of cheating someone or betray

Don't trust him ,he may double cross you. 不要相信他，他可能在騙你。

If you double cross someone you will get a bad reputation.  假如你欺騙人你會很壞的名聲。

How to stop double-crossing is a big educational problem.  如何製止欺騙行為是教育最重要的問題。