固定短语every so often：sometimes but not very often, from time to time, occasionally
可译为：不时地、有时候（但不是经常地），常常；请看经典例句：
The geologist needs to know what rocks the drill has reached, so every so often a sample is obtained with a coring bit. 地质学家需要知道钻头已到达什么样的岩层，因此时常要用芯钻头取样。（新概念英语4 Lesson 13 The search for oil）
Every so often the horse's heart and lungs are checked.
不时检查那匹马的心脏和肺。
Every so often he would turn and look at her.
他会时不时回头看她一眼。
Living in the city is nice, but we still try to go to the countryside every so often.
在城市住挺好的，但是我们还是尽量偶尔去乡下。
Every so often, a new martial art arrives from the East.
时而会从东方传来一种新的武术。
Every so often the kitchen would be invaded by ants.
厨房常常会遭到大批蚂蚁的进犯。
You're bound to mistime a tackle every so often.
有时候你肯定会错估铲球的时机。
We meet every so often and compare notes.
我们时常碰头，交换意见。
Every so often she takes a weekend in London.
她有时在伦敦过周末。
I no longer see him regularly, but he drops in at my office every so often.
我现在已不再经常去看他，但他却不时地到我办公室来。
