A temperamental person is someone whose mood often changes very suddenly.

Be careful how you approach her - she's very temperamental. 同她接触你要注意方式——她这人喜怒无常。

caused by your own character and feelings

There are temperamental similarities between the brothers. 兄弟俩在性情上有些相似。

A temperamental machine sometimes works and sometimes does not.

You have to treat our DVD player very carefully - it's old and temperamental. 你用我们的光盘机时得格外小心——它很旧了，而且性能不稳定。