play fair
do what is right to others；act in a fair and truthful way公平；举止正派
He is a hardnosed man， but you can be sure that he'll play fair with you．他虽是一个顽固的人，但是你放心，他一定会公平对待你的。
It wouldn't be playing fair if you were to break your promise at the last minute．你如果在最后关头失信的话，那就不近情理了。
play false cheat；deceive欺骗
Don't try to play me false； I can see you don't mean what you said．别想骗我，我看得出来你讲的跟你想的不是一回事。
Good faith was not in him；he played anyone false who trusted him．他一点也不老实，专门欺骗那些信任他的人。