[求助]TT GWD-3-8

Q8:A sudden increase in the production of elephant ivory artifacts on the Mediterranean coast of North Africa occurred in the tenth century.  Historians explain this increase as the result of an area opening up as a new source of ivory and argue on this basis that the important medieval trade between North Africa and East Africa began at this period.

Each of following, if true, provides some support for the historians’ account described above EXCEPT:

1. In East Africa gold coins from Mediterranean North Africa have been found at a tenth-century site but at no earlier sites.
2. The many surviving letters of pre-tenth-century North African merchants include no mention of business transactions involving East Africa.
3. Excavations in East Africa reveal a tenth-century change in architectural style to reflect North African patterns.
4. Documents from Mediterranean Europe and North Africa that date back earlier than the tenth century show knowledge of East African animals.
5. East African carvings in a style characteristic of the tenth century depict seagoing vessels very different from those used by local sailors but of a type common in the Mediterranean.

本题答案为D。我的疑问是B，B我理解为--10世纪前，很多北非商人留下来的信件中没有提及有关与南非的商业来往。难道这句话support原文的观点吗？原文观点是那段时间北非和南非之间有贸易往来。

那意思就是:

说A和B之间在某段时间发生关系，如果说A和B在这段时间前没有发生关系时，可以产生支持的效果罗？

仔细想想，有点感觉，不过挺微弱。

就上述例子而言，是不是这样说了之后缩小了范围，排出之前发生的可能性。这样就产生支持的效果。

B 有支持作用

原文：important medieval trade between North Africa and East Africa
            began at this period.

B说之前没有，那么那时开始有贸易往来也是合情合理的。

D说知道动物。没啥支持作用

Support中,有充分"支持"和"不充分支持"两种,不充分支持是GMAT常考题型.