on occasion

I don’t smoke cigarettes but I like to smoke a cigar on occasion.

我不抽烟，不过抽支雪茄。

Everyone should indulge in fantasy on occasion.

每个人都应沉浸在想像之中。

He was gifted, on occasion, with a gentle raillery, which almost always concealed a serious meaning.

他一有机，总爱说一些温和讥诮言词，但几乎每次都含着严正意义。