I should've listened to him. 我早该听他的话.
I should've stayed home. 我真不该出来. I wish I had known. 要是我早知道就好了. I should've done this long ago. 这件事我早该做了.
You can't relive yesterday. 你无法使时光倒流. I thought I was doing the smart thing. 那时我还以为自己在做聪明事儿呢? It's never too late to mend. 亡羊补牢,犹未为晚. What's done is done. Now let's consider the future. 逝者已矣, 来者犹可追. It's never too late to change. 随时悔改, 都不算太迟.
