老外也说 "放飞自我"，放飞自我就是随意不拘束，可不是真的要 "起飞"所以表达中不能用Fly这个词。
let myself go
行为放松不拘束
习惯和外形懒于修饰
放飞自我；不修饰自己
可以用来说
放纵自己吃胖，或社交中不加掩饰的真性情I've let myself go in the past 2 months and gained 5 kilograms.前两个月太放飞自我，我胖了5公斤。You should come to the party and let yourself go.你应该来参加party，放飞下自我。Let it go 是放飞什么？
说这话时
it=你过不去的那道坎
所以let it go= 放手，释怀
拿来开导有心事的朋友很好用
I still miss him since we broke up 2 years ago, what should I do?分手2年了我还想他，我该怎么办？You should let it go and move on.你该释怀，往前看。
Let it be 什么意思？
let it be = let it be （what it will be）= 顺其自然，爱咋咋
表达自己不想干涉事情的态度，就很酷
Your boyfriend hasn't talked to you for 2 weeks.你男朋友2周没理你了。Whatever，let it be.管它呢，爱咋咋吧。
Let's say 不是让我们说！
Let's say = 假设；比如
就像访谈节目里主持人说“咱们来说说，如果…，你会怎样？”
Let's say you have 5 million yuan,what would you do?假如你有500 万，你会干啥？I don't even have 5 yuan,so I don't have time to think about it .我连5块都没有，我可没时间想这个问题