急问一题：CD3 第二题

Guidebook writer:  I have visited hotels throughout the country and have noticed that in those built before 1930 the quality of the original carpentry work is generally superior to that in hotels built afterward.  Clearly carpenters working on hotels before 1930 typically worked with more skill, care, and effort than carpenters who have worked on hotels built subsequently.

Which of the following, if true, most seriously weakens the guidebook writer’s argument?

A.   The quality of original carpentry in hotels is generally far superior to the quality of original carpentry in other structures, such as houses and stores.

B.   Hotels built since 1930 can generally accommodate more guests than those built before 1930.

C.   The materials available to carpenters working before 1930 were not significantly different in quality from the materials available to carpenters working after 1930.

D.   The better the quality of original carpentry in a building, the less likely that building is to fall into disuse and be demolished.

E.    The average length of apprenticeship for carpenters has declined significantly since 1930.
            

答案为D，不太明白，麻烦哪位大牛给我讲讲。万分感谢！

这个ＷＲＩＴＥＲ说他访遍了全国的旅馆发现：大体上１９３０之前的旅馆的木工活要比１９３０之后的好，以此得出结论：１９３０之前的木工们worked with more skill, care, and effort than １９３０之后的木工，如果正如Ｄ所说，木工质量越好的房子越不容易被摧毁那么现在留下的１９３０前的房子都是质量好的＿＿举个例子比如说１９３０之前一共造了１０００所房子结果留下了２０所，但１９３０后一共造了２０所房子有１５所质量好，虽然现存的１９３０总体质量是比１９３０后的好，但不能说１９３０之前的木工比１９３０后的worked with more skill, care, and effort，毕竟９９８０的１９３０之前的房子都已倒了，不知它们的木工活做的怎么样＿＿也就是说１９３０前的房子样本太小或样本没有代表性＿＿成功地削弱了由１９３０之前木工worked with more skill, care, and effort这一原因，而导致１９３０之前房子木工质量比１９３０后好