句子：For instance, although evidence was found of deforestation, you know, cutting down trees, from at least 7,000 years ago, that is long before we'd thought previously.

问1：evidence was found of deforestation.中of deforestation是修饰evidence的吗？这是种什么语法现象呢？

【答】在evidence was found of deforestation中，显然of deforestation是修饰evidence的。正常词序是：evidence of deforestation was found，由于主语太长，所以，定语of deforestation和被修饰语evidence，被谓语动词was found分隔。——这种现象叫做“词语分隔”或“成分分隔”。

“定语和被修饰语的分隔”举例（红色部分把定语和被修饰语分隔）：

The problem arose of what to do with the money.

I have a picture here of a man who knew the address.

We heard the story from his own lips of how he was stranded for days without food.

The time is coming to prepare for Christmas.

There is no report to us of any accident.

I must try to make as careful a study as I can of the accident.

问2：that is long before we'd thought previously.中we'd thought previously是省略了关系代词when或者which吗？这里long before...整体是表语，还是long是表语，before...是时间状语呢？

For instance, although evidence was found of deforestation, you know, cutting down trees, from at least 7,000 years ago, that is long before we'd thought previously.

【翻译】例如，尽管砍伐森林的证据已被发现，可你知道，从至少7000年前开始就砍伐树木了，这比我们先前认为的要早得多。

这个句子比较复杂。分析如下：

1. 让步从句：although evidence was found of deforestation,

2. 主句：you know, cutting down trees, from at least 7,000 years ago, that is long before we'd thought previously.

3. 在主句中：

（1）cutting down trees, from at least 7,000 years ago, that is long before we'd thought previously：是konw的宾语从句。

（2）cutting down trees, from at least 7, 000 years ago：动名词短语，作宾语从句的主语。属于“左偏置结构”用法，然后用that再重复一遍。也就是说：cutting down trees, from at least 7, 000 years ago 等于that。

关于此结构，可分两种情况：

1.“左偏置结构”。（English Left Dislocation）

2. “右偏置结构”。（English Right Dislocation）

语法学上的“偏置结构”，就是把主语放在句子左侧或右侧，用不同的说法，再把主语重复一遍。这两种偏置结构，都是用不同的词语突出强调句子的主语成分。在现实语言中，尤以“左偏置结构”为多。英语的“偏置结构”属于非正式语体，但在新闻和演讲等较正式的言语交际中并不鲜见，这与其独特的结构和功能有关。其主要功能为了简化句式或强调某种信息。

4. 分析：that is long before we'd thought previously结构。

我们用cutting down trees from at least 7, 000 years ago替换that：

Cutting down trees from at least 7, 000 years ago is long before we'd thought previously.

本句中的is的意思，不表示“是”，而是不及物动词，相当于happens。直译就是：“砍伐树木一事，在我们先前认为的老早以前就发生了”。

从意思看，is是不及物动词happens的意思，long before we'd thought previously是时间状语。单纯从看结构上，long before we'd thought previously从句作is的表语，也可。但是，long不可单独作表语。