I think I've got the flu. 

我觉得我感冒了。

I've got a bit of hangover. 

我有点宿醉未醒。

I feel absolutely awful.  My temperature is 41℃, and I've got a headache and a runny nose. 

我感觉糟糕透了，体温41度，头疼流鼻涕。

It's really hurt.

真的很疼。

I feel dizzy and I've got no appetite. 

我头晕，并且没有胃口。

You don't look too well, maybe you should take the day off from work. 

你看起来气色不太好，或许你应该请假休息一天。

A: You don't look too well, maybe you should take the day off from work.

你看起来气色可不太好，也许你应该请一天假。

B: I couldn't do that. I have an important meeting to go to today.

我不能请假，今天我有个很重要的会议要参加。

A: Do you feel okay?

你觉得还好吗？

B: Not really. After a twelve-hour flight, I've got jetlag and on top of that, I think I've also got the flu.

不怎么样坐了12个钟头的飞机，时差还没倒过来，更要命的是我觉得我还感冒了。

A: Why don't you call your secretary and tell her to reschedule the meeting? You should really get some rest, or you'll end up feeling even worse than you do now.

你为什么不给你的秘书打个电话，让她重新安排你今天的会议呢？你应该好好休息，否则过一会儿可能会比现在感觉更难受。

B: Could you feel my forehead and check to see if I have a fever?

你能不能摸摸我的额头，看我是不是有点发烧？

A: You're really hot. Let me get you some medicine.

真的很热，我去给你找点药吧。

B: Okay. I'll stay home this morning and rest. But if I feel better in the afternoon, I'm going to go to the meeting. 

好的，我今天上午就呆在家里休息了。不过如果我下午感觉好一点的话，我还得回去开