I'm so depressed.

　　我很郁闷。

　　I feel so upset.

　　我觉得很沮丧。

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

　　我今天心情不好。

　　I feel kind of blue today.

　　我今天有点「郁闷」。

　　I feel low today.

　　我今天心情(有点)低落。

　　I'm so down.

　　我心情很低落。

　　I'm a bit down in the mouth today.

　　我今天有点闷闷不乐的。

　　I've been down in the dumps recently.

　　我最近很「郁闷」。

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

　　我不晓得什么地方不对劲儿。

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

　　抱歉，我今天心情不好。

　　I don't feel like doing anything.

　　我提不起精神来做事。

　　I got the short end of the stick

　　这实在是我所能遇到最糟的情况了。