occasion造句

On another occasion I answered the phone and the line went dead.
还有一回,我一接电话,就掉线了。

How can anyone look sad at an occasion like this?
在这样的场合怎么会有人显得忧伤呢?

It is, however, necessary on occasion to work outwith these hours.
然而,有时候在这些时点之外也需要工作。