100．Proponents of artificial intelligence say they will be able to make computers that can understand English and other human languages，recognize objects，and reason as an expert does--computers that will be used to diagnose equipment breakdowns, deciding whether to authorize a loan，or other purposes such as these．

(A)  as an expert does-computers that will be used to diagnose equipment breakdowns，deciding whether to authorize a loan，or other purposes such as these

(B)  as an expert does，which may be used for purposes such as diagnosing equipment breakdowns or deciding whether to authorize a loan

(C)  like an expert-computers that will be used for such purposes as diagnosing equipment breakdowns or deciding whether to authorize a loan

(D)  like an expert，the use of which would be for purposes like the diagnosis of equipment breakdowns or the decision whether or not a loan should be authorized

(E)  like an expert，to be used to diagnose equipment breakdowns，deciding whether to authorize a loan or not，or the like

C is correct.

我的问题是:

1. C中“——”起解释说明的作用，相当于定语从句,既然是定语从句,那为什么不是like an expert-computers  will be used for ..., 而用that从句来修饰computers呢?

2.原文抽出主干为：they will be able to make computers that can understand...,recognize..., and reason like an expert --computers that will...,

computers that will 又好象是同位语,是谁的同位语呢?前边的compurers吗?自己做自己的同位语吗?

翻看了以前所有的讨论,还是不明白.请大家帮帮忙!!!谢谢!

1,一个介词短语（like an expert-computers  ）怎么能作先行词呢?这里重新提出computer的目的就是为了防止定语从句修饰混淆。（防止混淆的方法1，重新写出修饰对象。2用such/this/that/these/those等指示代词+名词的方式重新强调修饰对象。3，用一个概括性名词强调修饰对象）

2，破折号后面为computer的同位语。这本身就是同位语的一种形式，noun, noun that...第二个noun重复第一个noun引出同位语从句