Ⅱ.重点句型详解

They lived on the earth tens of millions of years ago, long before humans came into being...

千百万年前它们(恐龙)就在地球上生活，比人类的出现要早得多……

long before 早在……之前很久

before可做连词，连接时间状语从句，做介词，连接时间点或做副词。long before 连接的时间状语从句用一般现在时呼应主句的一般将来时；一般过去时呼应主句的一般过去时或过去将来时。

拓展：(1)before long “不久以后”，相当于 soon after/shortly after, 既可以指将来，也可以指过去，所以与过去时或将来时连用，在句中做状语，不可以引导从句。

(2)long ago (现在的)很久以前。

(3)“It will be long before＋从句(一般现在时)”与 “It was long before＋从句(一般过去时)”的意思是“过很久才……”，强调经过的时间长。

(4)“It will not be long before＋从句(一般现在时)”与“It was not long before＋从句(一般过去时)”，意思是“没过很久就……”，强调经过的时间短。

注意：以上短语、句型中的 long均可以改用普通的时间名词或短语，表达不同的时间长度。

①Long before, there was a big museum here.

很久以前，这里有一座大博物馆。

②I had heard of him long before I came here.

早在我来这儿很久以前我就听说过他的情况。

③Before long he went to Canada to go on with his further education.不久以后他就去加拿大继续深造了。

④It was not long before she came. 没多久她就来了。

⑤It will be long before we see each other again.

我们很久以后才会再见面。

[即境活用]The book was published ______ it was written.

A．soon before　　　B．long before        C．before long        D．soon after

解析：句意为“书写完后不久就出版了”，故选 soon after。

答案：D