A) Bears have done great harm to the forest by littering their half eaten salmons.
B) Bears have destroyed the environment by destroying the forest.
C) Bears have actually left many salmons to the forest.
D) Bears have actually provided nutrients to the forest by littering their half eaten salmons.
3. Young salmons live in .
A) the fresh water
B) the sea
C) the gravel on the ground
D) the pond
4. Why does the influx of energy from the ocean have great effect on freshwater systems?
A) Because the salmons have brought back a large number of other fishes.
B) Because most young salmons die at sea and they produce much nutrition.
C) Because the nutrient composition of the fish and their densities are so great.
D) Because death of adult salmons at sea produces a large number of nutrients.
5. In order to survive in the winter days, the brown bears depend heavily on the salmon for their .
A) protein
B) drinking
C) fat deposit
D) meat
6. To protect the salmon it gets from being taken by others, a bear usually take the fish into .
A) the forest
B) the river
C) the sea
D) the den
7. Being selective, the bear only eat .
A) the most tender part of salmons
B) the most nourishing part of salmons
C) the most delicious part of salmons
D) the most delightful part of salmons
8. The feeding behavior of the bears can be interpreted as bringing the nutrients from the ocean to the _______________.
9. After the bears finish with their part of the salmon, many other creatures ca benefit from the leftovers ___________________.
10. By supplementing the nutrients needed by the plants ear river side, the bear feeding activities ca have certain influence on the plants' ______________.
答案：文章梗概：
本文阐述了棕熊捕食鲑鱼对河边生态的重要作用。首先由人们对棕熊捕食鲑鱼产生的误解引出科学研究的结果——棕熊实际上给森林提供了养料。之后介绍了鲑鱼生命周期的特点及其对棕熊的影响。接下来介绍了棕熊捕食行为的两个特点，指出这些行为把海洋养分带给河边生态系统，使很多生物受益。
答案解析：
1. 由题干关键词fishery managers和hungry bears定位至第一段第二句 The hungry bears… fishery managers, who in the late 1940s proposed their broad scale culling in Alaska to reduce the "economic damage" the predators might be wreaking on salmon populations. 大意是：这些饥饿的熊引起了一些渔业管理人员的注意，他们在40年代曾提出大规模剔除阿拉斯加的熊，以便减少这种掠食者对鲑鱼数量的"经济破坏".故C)正确。
2. 由题干关键词bears和forest定位至第三段第三句Our findings surprised us: bears actually fertilize the forests, nourishing them by discarding partially eaten salmon carcasses. 研究使我们吃惊，熊通过丢弃吃剩下的鲑鱼残骸给森林提供了养分。因此D)的表述与原文相符。
3. 由题干关键词Young salmon定位至第四段第二句Young salmon emerge from the gravel in streams or lakes in spring and then… migrate to the ocean. 大意是：鲑鱼幼年时生活在小溪河湖中，然后移居海洋。故A)正确。
4. 由题干关键词the influx of energy定位至第五段第一句This influx of energy from the ocean can have an extraordinary effect on freshwater systems because the nutrient composition of the fish and their densities are so great.该句谈的是:海洋能量的流入对河流有巨大的影响是因为迁徙回来的大量鲑鱼身上储存的营养成分，因此答案应为C)。
5. 由题干关键词brown bears和salmon定位至第六段第二句Salmon are a crucial resource for the bears because the survival and reproductive success of these large mammals depend on the amount of fat they can deposit in the late summer and fall. . . . 鲑鱼是棕熊的重要资源，因为这些巨大哺乳动物的生存和繁殖都依靠它们在夏秋时节积累的脂肪。因此选C)。
6. 由题干关键词protect the salmon. . . from being taken定位至第七段最后一句Carrying the carcass into the forest out of sight of other bears is a way to avoid confrontation. 根据前面一句，此处的对抗是指棕熊之间对鱼的争夺或其他生存斗争。因此答案为A) the forest.
7. 由题干关键词only eat the part定位至第八段第一句The second important behavior is that the bears often eat only the most nourishing part of the salmon. 棕熊的第二种重要行为是它们通常只食用鲑鱼最有营养的部分。因此答案为B)。
8. 由题干关键词feeding behavior和the nutrients from the ocean定位至倒数第四段最后一句The bears are truly ecosystem engineers: they deliver marine-derived nutrients to the river side system. 棕熊真不愧为生态系统的工程师：它们把来自海洋的养分运送到河边的生态系统中。由此可见，题干是对这句话的转述，因此答案应为river side system.
9. 由题干关键词other creatures can benefit定位至倒数第二段第一句A creature does not have to consume the salmon directly to benefit from the ocean's gift. 生物并不一定要通过直接吃到鲑鱼才能享受到海洋的馈赠。从这句话中的does not have to consume the salmon directly可知，很多动物都直接或者间接地受益于棕熊的进食行为。当然，这也可由上文中的…many different animals make use of the protein and fat in the abandoned fish得道印证。因此，空格的内容可以总结为directly and indirectly.
10. 由题干关键词have certain influence定位至最后一段第二句…and thus the bears' feeding activities may influence growth rates of many plant species in these areas.由此可见，题干是该句的同义转述，根据句意, 答案应该是growth rates.