【题目】Whether the declining of bison was caused by the European American settlers.
【阅读】About bison, a kind of animal, something like cattle or horse. The passage suggests that the declining bison was due to the European American settlers:
1. When European American cross prairies, they hunted bison as food because there is no food in prairies.
2. They brought cattle and horses, which competed with bison for resources.
3. The evolving technology, especially guns, let hunters kill several bison in a short time.
【听力】The professor contradicts each of these three points:
1. The European American moved from east to west, but the bison decline in the western part of America. The pattern of how bison disappeared gradually was different from that of movement of European American.
2. Bison have double furs covering their bodies and unique head structure, which allow them to live in harsher and colder areas. The areas were unreachable for cattle and horses. How could different spices compete with each other in separate territories?
3. The advanced technology should not be blame worthy for the decreasing bison. The ancient methods are as effectively as guts. Skilled ancient American hunters could kill several bison with short intervals.
2. 2亿年前连flowering plants都没有，怎么会有需要吃花蜜的蜜蜂；
2. 古时候的蜜蜂就一定要吃花蜜吗？他们不能吃nonflowering plants吗？
3. 没有盖子cap可能因为化学原因， 腐蚀掉了什么的，再说为什么要跟modern bee一样呢？
1. Fossils of saber-toothed cats with broken bones indicate that they were fed by other saber-toothed cats when they were injured
2. There are large numbers of saber-toothed cats in the trap. The saber-toothed cats hunted together. The sound of dears in the trap attracted them to fall in the trap together
3. Saber-toothed cats lived with other predators such as lions and wolves. Saber-toothed cats have to live in group to compete with those predators.
1. The fossils of saber-toothed cats with broken bones indeed indicate that they could survive when they were injured. However it doesn’t necessarily mean that they have to be fed by other saber-toothed cats. Many predators can find dead animals to eat. So did the saber-toothed cats
2. The large numbers of saber-toothed cats in the trap doesn’t mean that they hunt together. The saber-toothed cats hunt separately. One of the saber-toothed cats heard the sound of the trapped dear, went to the trap and fell. Then another saber-toothed cat also heard the sound of the trapped dear, came to the trap and fell again
3. Saber-toothed cats were large predators. Take tigers for example, one tiger is strong enough to fight against the social predators such as lions and wolves. So the saber-toothed cats don’t have to live together to compete with lions and wolves.
【题目】whether the canned food is the factor that contributes to the lead poisoning and the death of crew in Kaship。
1. The lead that was carefully stilled to the can would not contact the food.
2. No other evidence of death of the crew was found in other ship.
3. Water purification system may be the source of poisoning.
1. Company has limited time to finish this work. Workers are under time pressure and it is reasonable that they are careless and apply lead to the cans in a hurry way.
2. First, it is difficult to judge whether sailors are affected by lead without careful tests. Second, the symptoms of lead poisoning are common, such as feeling tired or headache and they can be easily overlooked.
3. The water in the purification system is used for ship engineering since the salt water cannot be used. The water for cooking and drinking comes from a different way.
1. 第一个理论：没有帮助。因为植物没有internal heat,在遇到冷的天气，尤其是冰点以下时不能避免冻害。