keep your head straight 和keep your head on straight有何区别

keep straight
(使)行为端正；(使)过正直生活；使循规蹈矩
be on the straight品行端正
词典上可以查到,区别不大.这里的意思基本是表达直起头部，但是在意思上有细微差别，能不能从这个角度上谈谈区别，谢谢！keep your head straight 就是直起头部keep your head on straight 是保持头脑清醒例如：Keep your head on straight and you will avoid being swept off your feet by someone promising you the world but offering little.保持头脑清晰，向前，你将避免被骗。对方可能许诺了很多，但是兑现的很少。