Bible两个Weaken问题求教前辈们

chenlang4869

第一个题如下：
Archaeologist: A skeleton of a North American mastodon that became extinct at the peak of the Ice Age was recently discovered. It contains a human-made projectile dissimilar to any found in that part of Eurasia closest to North America.Thus, since Eurasians did not settle in North America until shortly before the peak of the Ice Age, the first Eurasian settlers in North America probably came from a more distant part of Eurasia.
Which one of the following, if true, most seriously
weakens the archaeologist’s argument?
(A) The projectile found in the mastodon does not resemble any that were used in Eurasia before or during the Ice Age.
(B) The people who occupied the Eurasian area closest to North America remained nomadic throughout the Ice Age.
(C) The skeleton of a bear from the same place and time as the mastodon skeleton contains a similar projectile.
(D) Other North American artifacts from the peak of the Ice Age are similar to ones from the same time found in more distant parts of Eurasia.
(E) Climatic conditions in North America just before the Ice Age were more conducive to human habitation than were those in the part of Eurasia closest to North America at that time.

第二个题如下：
Lobsters and other crustaceans eaten by humans are more likely to contract ill diseases when sewage contaminates their water. Under a recent proposal, millions of gallons of local sewage each day would be rerouted many kilometers offshore. Although this would substantially reduce the amount of sewage in the harbor where lobsters are caught, the proposal is pointless, because hardly any lobsters live long enough to be harmed by those diseases.
Which one of the following, if true, most seriously
weakens the argument?
(A) Contaminants in the harbor other than sewage are equally harmful to lobsters.
(B) Lobsters, like other crustaceans, live longer in the open ocean than in industrial harbors.
(C) Lobsters breed as readily in sewagecontaminated water as in unpolluted water.
(D) ill diseases cannot be detected by examining the surface of the lobster.
(E) Humans often become ill as a result of eating lobsters with ill diseases.

关于第一个题的题干，说的是，一个在冰川鼎盛时期灭绝的北美乳齿象的骨骼被发现，它有一个human-made projectile，和在距离北美最近的欧亚大陆部分地区发现的都不一样（不知道理解对了没有）。因为欧亚大陆人在冰川鼎盛时期前不久才在北美settle，所以结论是，第一个来北美settle的欧亚大陆人一定是来自于更远欧亚地区的。这里作者推出这个结论的逻辑是什么？想了很久都没有想明白。因为没有搞清这个逻辑，所以weaken不好下手。

第二个问题，说龙虾在污水中更容易聚集疾病。最近的一个研究表示，即使是把大量的污水不排入龙虾所在的港口，减少水污染，就算这样也是徒劳，因为极少有龙虾会在活着的时候harmed by the disease.  这里难道不是矛盾的么？龙虾活着的时候不会感染疾病，而第一句话又说be more likely to contract ill disease. 于是脑子里就开始浆糊了

以上两个问题，请论坛前辈指点。