early

early, early on

early on原为英式英语,现在美式英语也通用,在非正式文体中须去掉on。其意思是“初时,在较早的阶段,早些时候”。有些语法学家认为这和later on一样属于用词不够经济的例子,但在实际英语中, early on经常有人用。例如:
Mary came to see you earlier on, but you weren't at home then.玛丽早些时候来看望过你,但你当时不在家。

early, ago

两者都可表达“某时之前若干时间”。它们的区别在于:如果是从现在起向过去推算,用表示时间度量的短语加ago,并与动词的一般过去时连用; 如果表示从过去时刻向更深远的过去推算,则用earlier,并常与动词的过去完成时连用。例如:
Stirring scene from the film still sticks in my mind, though I saw it several years ago.虽然这部影片我是几年前看的,但那激动人心的场面仍然印在我的脑海里。
Four days earlier his foot had been bitten by a poisonous snake.4天前他的脚被毒蛇咬了一下。

early, quick, shortly, soon

这组词共同的意思是“不久”“即刻”“快”。它们的区别在于:early常指时间比原来或通常早些; quick含有匆忙、仓促之意; soon指在某一特定时间过现在之后不久,多用于将来时或过去时,通常放在句末或主要动词之前; shortly与soon同义,但比soon更郑重,常用于新闻报道等。例如:
You have to think quick with the mind and act quick with the body.你必须脑子转得快,行动也得快。
I came early, and had to wait for others, but soon after five o'clock they appeared.我来得早,得等其他人,可是刚过5点他们就都来了。
Shortly after that, the police arrived.那事情发生不久警察就到了。