off and on是什么意思？据说该习语源于早期铁路故障，那时铁路脱轨（off the track）是很常见的事情，只要扳正（on the track）就行了。
所以后来也就引申为“断断续续”。

链接：
断断续续，时断时续：
on and off;
off again,on again;
on again,off again.

1.The idea of being a writer bad come to me off and on since childhood,but it wasn't until recently that the possibility took hold.
从孩提时代，我就断断续续地有当作家的念头，但直到最近，这一想法才有了实现的可能。

2.Recently it rained off and on every day.
近来每天都在断断续续地下雨。

3.He has been writing to us off and on for several years.
他断断续续地给我们写信已经有好几年了。

4.Uncle George tippled off and on.
乔治叔叔偶而喜欢喝一杯。