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?

1. 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.
2. Hotels built since 1930 can generally accommodate more guests than those built before 1930.
3. The materials available to carpenters working before 1930 were not significantly different in quality from the materials available to carpenters working after 1930.
4. The better the quality of original carpentry in a building, the less likely that building is to fall into disuse and be demolished.
5. The average length of apprenticeship for carpenters has declined significantly since 1930.

说1930年以前的木工做出来的酒店质量要比后来建的酒店要好,得出结论说是因为1930年前建造酒店的木匠比后来的更有技术,更努力.问削弱.

A拿酒店木工的质量和别的建筑的木工质量比，明显不相关;B说酒店能容纳多少人也不相关;C好象是个assumption;E说1930年后木匠做学徒的时间大大下降,有点support的感觉,当然不能说做学徒时间下降技术就一定要比以前差,也可以说不相关.

那么这样看来只有D说一个建筑最初的木工质量越好,越不可能被损坏,与现在guidebook writer看到的情况1930年以前的酒店木工质量好是一致的.好象只是在说质量好,并没有解释为什么质量好.

楼主选哪个啊,我也有疑问呢.

烦请路过的xdjm给个解释,谢谢了

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

也就是说保存时间越长的，质量就越好，即the quality of original carpentry in a building before 1930 is better than that after 1930. 这样通过提供他因起到削弱的作用。