while ,the moment ,once 用法区别(英语语法)

while ：conj. 当……的时候；虽然；然而
n. 一会儿；一段时间
vt. 消磨；轻松地度过
the moment ：立刻,马上；一…就
once：adv. 一次；曾经
conj. 一旦
n.一次,一回
adv.一次；曾经
n.一次,一回
他们意思本身就不一样：几个例句：
I once interviewed him for a job.
我曾经为一份工作面试过他.
Once I nourished the entire human race .
过去,我曾经养育过整个人类.
Most people have had the experience at least once.
大多数人至少曾有过一次这样的经历.
You must be off antibiotics for a while.
你必须停服一段时间的抗生素.
After working with Operation Smile for a while.
在“微笑行动”工作了一段时间后.
Some courses in college are required while others are optional.
大学里有的课程是必修的,有是是选修的.
But the moment never seemed right.
但时机似乎永远都不大对.
Such targeted taxes seem to be in vogue at the moment.
当前这种有针对性的征税似乎在成为时尚.
At the moment, ethanol—whether for wine, beer or fuel—is made by fermenting sugar or starch.
目前,不论是红酒、啤酒还是汽油中的乙醇,都是通过糖或淀粉发酵而得.