请教补充材料P163,Q20

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Archaeologists seeking the location of a legendary siege and destruciton of a city are excavating in several possible places, including a middle and a lower layer of a large mound. The bottom of the middle layer contains some pieces of pottery of type 3, known to be from a later period than the time of the destruction of the city, but the lower layer does not.

The force of the evidence cited above is most seriously weakended if which of the following is true?

A.Gerbils, small animals long native to the area, dig large burrows into which objects can fall when the burrows collapse.

B.Pottery of types 1. and 2, found in the lower level, was used in the cities from which, accroding to the lengend, the besieging forces came.

C.Several pieces of stone from a lower-layer wall have been found incorporated into the remains of a building in the middle layer.

D.Both the middle and the lower layer show evidence of large-scale destruction of habitations by fire.

E.Bronze axheads of a type used at the time of the siege were found in the lower level of excavation.

本人选的是D,可是正确答案是A,从内容上看A与文章没有一点关联，请那位DX指教。A是用何种方法来weaken的

[此贴子已经被作者于2004-8-31 19:57:53编辑过]

joe11

他因。

由于有Gerbils挖洞才造成这种现象，并不是 type 3 本身存在于 the bottom of the middle layer 。

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thanks