Art museums do not usually think of their collections as capital or consider the interest income that would be generated if a portion of the capital would have been invested in another form.

(A) be generated if a portion of the capital would have been

(B) have been generated if a portion of the capital would have been

(C) be generated if a portion of the capital were

(D) be generated if a portion of the capital was

(E) be generated if a portion of the capital had been

答案是C，可是我查了一下朗文英语词典，无论是从a portion of的角度还是capital的角度，主语都应该是单数吧，所以我觉得D选项比较合适。各位朋友有时间帮忙看一下吧，实在是很困惑，还是有什么其他机关我没看出来呢？

非常感谢。

个人觉得是C

这里实际上是一个虚拟语气，所以在虚拟语气里面 if虚拟语气 表达和现在情况相反的时候 be动词一律使用were

整句话的意思是：（按照字面翻译）　艺术博物馆经常不把他们的收藏品看作是资本，也不去考虑那些由投资部分该类资本于其他形式所可能创造出的利润。

这里主句所使用的是一般现在时态，阐述经常性习惯性的动作

而that限定定语从句，将that从属连词替换为the interest income 这句话就变成了： the interest income would be generated if a portion of the capital were invested in another form.

那么现实中这个capital投资了么？ 实际上是没有的，也就是说该句描述了一个与现实相反的例子 应该使用虚拟语气 were

另一个虚拟语气的证据是那个没有划线的would 这也是if虚拟从句描述与现在事实相反的常用结构