sine qua non
(fml 文) essential condition; thing that is absolutely necessary 必要条件; 必不可少的事物
Patience is a sine qua non for a good teacher. 做个优秀教师必不可少的条件是要有耐心.
I didn't catch that, Could you go over that again?
我没有听清楚,请你再说明一下好吗?
A telescope would have to be as far away as the planet Jupiter to look for life in outer space, because the dust becomes thinner the further we travel towards the outer edges of our own solar system.