Archaeologists in Egypt have excavated a 5,000-year-old wooden hull that is the earliest surviving

example of a "built" boat--in other words, a boat constructed out of planks fitted together--and that

thus represents a major advance, in terms of boat-building technology, over the dugout logs and

reed vessels of more ancient vintage.

(A) together--and that thus represents

(B) together--and this has represented

(C) together, and it represents

(D) together that was representing

(E) together to represent

在语法考试中，that, this, those 等代词无法单独使用，这里在 选项 A 和 选项 B 之间 这里除了B 选项的时态问题，A 选项里 的 that 为什么使用正确呢？

请大家指点

这里的that并不是代词，而是定语从句的引导词和前面那个that一样 所以之间使用and连接

句子结构为： Archeaologists in Egypt have done sth. that is .... and that represents ...

两个that引导的定语从句并列

这里的that不等于this/that/those的那个that，也就是，这里的that不是代词。

这里的that是定从引导词。

原文简写：

A have excavated WH that is ... and that represents ...

考点：两个定从的平行。

it 这个代词 就近指代， 而最近的名词是 boat , 逻辑上表达错误，所以不能用 it.

语法笔记上说破折号隔开的成分相当于插入语，去掉后不影响句子结构。

那这里的插入语是相当于哪一部分？是两个破折号之间吗， 还是最后一个破折号之后？

我有点搞不懂两个破折号的修饰关系。

请教。