Sure./Certainly./Definitely./Absolutely. 当然。

As soon as possible. 尽快。

That's enough. 够了。

It doesn't matter. 没关系。
It's not important. 不重要。
It's not serious. 不严重。
It's not worth it. 不值得。

I'm in a hurry. 我很急。
I've got to go. 我要走了。
I'm going out. 我要出门。

Sleep well! 睡个好觉!

Same to you! 你也是!

Thanks for your help/hospitality/email. 谢谢你的帮助/热情款待/邮件。

Sorry I'm late. 对不起我来晚了。
Sorry to keep you waiting. 对不起让你久等了。
Sorry for the delay. 对不起慢了一点。

Only joking!/Just kidding! 只是开个玩笑。

Bless you! (after a sneeze) (在人家打喷嚏后说)愿神保佑你。(因为西方人相信在打喷嚏的瞬间,灵魂会出窍,恶魔会趁虚而入)

That's funny! 真逗!

That's life! 这就是生活!

Damn it! 该死!

Is anything wrong? 有什么问题吗?
What's the matter? 出什么事了?
Is everything OK? 都好吗?