放下过去 move on
(1) move on “放下过去，向前看，开始新的生活”
英语解释为to stop focusing on someone or something in order to progress with other tasks or one's life.
(2) move on美剧中使用频率很高，用于表示遇到伤心事后，走出痛苦，开始新的生活。
如一段恋情结束后，走出阴霾，向前看，或者开始新的恋情；
再如亲人、朋友去世后，走出阴影，向前看；
又如放下过去的不开心、不如意，开始新的生活。
例
She hears her ex-boyfriend is dating again. He moves on so easily.
她听说前男友已经开始约会了，他那么快就放下过去了。
Could you just forgive her and move on?
你就原谅她，开始新的生活吧。
It's time we move on, I mean, don't you think?
我们该放下过去了，你不同意吗？《老友记》
抛之脑后 put sth. behind you
put sth. behind you “把某事抛之脑后，不再想某事，不再纠结某事，放下某事”，指忘掉不愉快的事或经历
英语解释为to try to forget about an unpleasant event or experience and think about the future。
例
No, just come over watching movie put the whole thing behind you.
不，把所有事都抛在脑后过来看电影吧。
She put the past behind her.
布里把过去抛到脑后。
Plus, I'm trying to put my story behind me.
况且，我在试着放下这段过去。
忘掉某人 get over sb.
(1) get over词典里的基本意思是“从（疾病中或不愉快的经历中）恢复过来”
英语解释为to return to your usual state of health, happiness, etc after an illness, a very upsetting experience etc。
(2) get over在实际使用时，可以根据使用情景，翻译成不同的汉语
(3) get over 用于男女感情时，get over sb.表示“忘记某人，忘掉某人”
可以理解为，从某人带给自己的痛苦中恢复过来，所以就是“忘记某人”了
(4) get over one's ex-boyfriend/ ex-girlfriend “忘掉前男/女友”
例
I can't get over you.
我忘不掉你。
It's hard for him to get over his ex-girlfriend.
忘记前女友对他来说太难了。
For a while there I never thought he'd get over the last one.
曾经我一度认为他永远也忘不了前女友。
