double cross 背叛，不诚实，欺骗他人的行为。

Double cross - the way of cheating someone or betray

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

If you double cross someone you will get a bad reputation.  假如你欺骗人你会很坏的名声。

How to stop double-crossing is a big educational problem.  如何制止欺骗行为是教育最重要的问题。