请教几道关于指代的问题 谢谢大家了真是搞不明白了

qhfzwyx

对于指代的两个规则： 从句中的代词优先指代主句中的主语，其次指代主句中的宾语；                                    并列句的代词优先指代第一个并列句中的主语，其次指代第一个并列句中的宾语
这两个规则谁更优先呢？
========================================================
具体针对以下两题:
36. (26354-!-item-!-188;#058&003133)
A group of paleontologists recentlyannounced that a site in Utah has yielded fossils of some of the biggest armored dinosaurs ever found,and that they were at least 25 million years older than any similar dinosaur type previously found in North America.
(A) and that they were at least 25 millionyears older than any similar dinosaur type previously

(B) and they are at least 25 million yearsolder than those of any similar dinosaur type that
previously was
(C) and the fossils are at least 25 millionyears older than any similar dinosaur types that previously were
(D) fossils that are at least 25 millionyears older than those of any similar dinosaur type previously
(E) fossils at least 25 million years olderthan similar dinosaur types previously
对于语法笔记中的解析有一点不明白：
(B) they 指代不清楚。（不是应该优先指代并列句中的复数名词吗？那不就是fossils??）；错误是因为thatpreviously was 累赘？
(D)  正确，fossils that…是同位语，those 指代 fossils。同位语结构避免了 they 代词指代的歧义。
========================================================
49. (27096-!-item-!-188;#058&003405)

Since 1990 the global economy has grownmore than it did during the 10,000 years from the beginning of agriculture to 1950.
(A) Since 1990 the global economy has grownmore than it did during the 10,000 years from the beginning of agriculture
(B) Since 1990 the growth of the globaleconomy has been more than that during 10,000 years, from when agriculture began
(C) The growth of the global economy since1990 exceeds that which had been for 10,000 years from the beginning of agriculture
(D) The growth of the global economy since1990 exceeds what it has been for 10,000 years, from when agriculture began
(E) The growth of the global economy since1990 exceeds what it did for the 10,000 years from the beginning of agriculture
(A)  正确，it指代economy，did指grow的过去时。
(D) it指代对象不清楚，表达罗嗦不清晰，且exceeds后面应该用过去时态，而不是现在完成时态；from+when引导的从句用法错误。
为什么it不是指代The growth of the global economy 呢？ 还是说因为it不指代核心词，所以这里的it 指代The growth of the global economy since 1990？
可是对比正确选项A，A中的it不是也指代 Since 1990 the global economy 么，难道是因为这里since 1990在句首是修饰全句？


求指教啊！！！！

qhfzwyx

帮帮忙吧麻烦各位~