1. occasionally
2. occasional
3. incidentally
例句与用法:
1. 他偶然说走嘴。
He had a slip of tongue by accident.
2. 我只是偶然抽一支雪茄。
I only smoke an occasional cigar.
3. 他偶然发现了这幅画。
He discovered the painting perchance.
4. 我们的相遇是很偶然的。
Our meeting was quite accidental.
5. 我偶然跟他闲聊, 一起说笑话.
He's someone I have an occasional chat and joke with.
6. 我遇见她完全是偶然的.
I met her quite by chance.
7. 我们（彼此）相遇纯属偶然.
We met (each other) quite by chance.
8. 我们只是在昨天才与她偶然相遇.
We met her only yesterday, as it happens.
