隔三差五的英文：
[Informal] (every) now and then; (every) now and again; every so often; time and again; from time to time

参考例句：

Why could he not have a woman of his own instead of these filthy scuffles at intervals of years?
干吗他没法有个自己的女人，只能隔三差五搞搞这种破烂货？

informal是什么意思：
adj. 非正式的；口语体的，通俗的；不拘礼节的

Informed judgement.
有事实根据的判断。

This is an informal expression.
这是一种非正式表达法。

This is an informal word.
这是一种口语用语。

every是什么意思：
det. 每一，每个；每隔，每；每…之中；充足的
adj. 每一的，每个的；所有的

Not every server in every restaurant can be relied upon.
不是所有的饭店服务员都可以信赖。

To triumph in every battle and succeed in every invasion
战胜攻取

His every act and every move are natural and unrestrained.
他的举手投足潇洒自然。

often是什么意思：
adv. 时常，常常；往往，通常

They often gossiped.
They often gossiped.

Often the good suffer, and often the wicked prosper.
好人总是受气遭殃，坏人往往青云直上。

She often keeps a diary.
她常记日记。