I couldn't help laughing.

我忍不住笑出来。

I really have to rush.

我真的得赶快走了。

I love you with all my heart.

我全心全意爱你。

He seems to be getting on very well at school.

他在学校似乎过得很好。

How long does your vacation last?

你的假期有多长？

Don't waste your breath trying to persuade them, they'll never listen.

别白费口舌规劝他们，他们不会听你的话。