prep 2#105 since与过去完成时+prove

105.
            2001 proved to be the automaker's first losing year since 1992, when the company had lost $7.4 billion, which was primarily because of almost $7 billion in accounting charges.

(A) when the company had lost $7.4 billion, which was primarily because of（时态；which简洁有效）

(B) when the company had lost $7.4 billion, primarily resulting from（时态）

(C) when the company lost $7.4 billion, primarily because of

(D) which is when the company lost $7.4 billion, and that was primarily because of（which is没有必要，that前面没有可并列对象）

(E) which is when the company lost $7.4 billion, primarily resulting from

此处when为非限定性定语从句，修饰前面的时间1992这一时间点，所以要用一般过去时，但是这个主句proved是不是应该改为have been proved to be 完成时态呢？

呵呵！～我想我大概是明白啦～ 实际上prove是发生在过去的一件事情，prove的具体内容是自1992年以来的first losing year。也就是说实际上since是被prove的一部分，而不是prove的发生的时间修饰～对吧～～亲爱的魔力小姐～