OG12 106 that指代。。。could 可任意添加？

WesternCder

OG12-106
Marconi's conception of the radio was as a substitute
for the telephone, a tool for private conversation:
instead, it is precisely the opposite, a tool for
communicating with a large, public audience.
(A) Marconi's conception of the radio was as a
substitute for the telephone, a tool for private
conversation; instead, it is
(B) Marconi conceived of the radio as a substitute
for the telephone, a tool for private
conversation, but which is
(C)   Marconi conceived of the radio as a tool for
private conversation that could substitute for the
telephone; instead, it has become
(D) Marconi conceived of the radio to be a tool for
private conversation, a substitute for the
telephone, which has become
(E) Marconi conceived of the radio to be a
substitute for the telephone, a tool for private
conversation, other than what it is,

答案为C

2个问题
1 that
有人说其中that跳跃修饰tool
根据OG12解释--- The main point of ths sentence is to explain that while Marconi felt the radio would substitute for the phone as an instrument of private communication, in fact ...
我觉得应该是指代radio.
2 could
原文中无could, 但选项中有could，说明添加了could， 问：情态动词不是不可以随意添加吗？

大家讨论一下。

dongstar

逗号+which，一般情况下要求which就近修饰临近的名词，而that引导的限定性定语从句，一般没有which那么严格 ，可以跳跃修饰，例如，the spoon is a tool for eating food that was invented in prehistoric times，that这里修饰spoon， that在这个题中就是修饰radio，OG中还有其他例子，楼主再找找

xiaotangyu

同意楼上看法。
另外，我同意情态动词是不可以随意添加，但不可因为看到原句A选项没有情态动词，而觉得其他有情态动词的选项distort meaning而去掉。一切要从logic看啊，我们要忠实作者要表达的意思，并非把A作为标准

brunhildS

其实，n+prep结构+that 这种结构中，that修饰n还是prep的宾语是具体问题具体分析的。也就是说that可以修饰n也可以修饰介词宾语。一般GMAC会用n和介词宾语的单复数不同帮你唯一的确定that修饰的是n还是介词宾语。但是此题因为radio 和tool都是单数，所以造成判断上有难度。这是，可以通过文章上下文的意思来推断。

zm_patrickS

1, 同意LZ和1楼的看法。n+prep结构+that这种用法可以跳跃修饰，我觉得是跳过介词结

构直接修饰中心词（n）。所以，C中的that其先行词为radio.
2, 首先可以肯定的是情态动词不能随意添加。这里之所以能用是因为could在这里表示过去

的意愿。如果这里不用could，substitute就需要用过去式substituted表示过去发生的事实。

但是，这与原意不符。因为（照我的理解）radio substituted for the telephone 并没

有实际发生。所以，这里用could 比substituted更加合适。

danni423

为什么修饰作用中的名词不用看呢？that就不能指修饰词中间的最靠近它的名词吗？

xiruihuang

1:我赞同你的观点，that修饰radio,因为as a tool ,for private conversation均是介宾短语，起修饰作用，可以略过不看，直接看主干，that就近直接修饰radio
2:我个人觉得是看需要增减情态动词