1. I'm so depressed.

我很郁闷。

2. I feel so upset.

我觉得很沮丧。

3. I'm in a bad mood today. / I'm moody today.

我今天心情不好。

4. I feel kind of blue today.

我今天有点「郁闷」。

5. I feel low today.

我今天心情（有点）低落。

6. I'm so down.

我心情很低落。

7. I'm a bit down in the mouth today.

我今天有点闷闷不乐的。

8. I've been down in the dumps recently.

我最近很「郁闷」。

9. I can't put my finger on what's wrong.

我不晓得什么地方不对劲儿。

10. Sorry, I got up on the wrong side of the bed today.

 抱歉，我今天心情不好。