2. 外语
  3. Second World War than in calling for women to return to domestic life after the war. Since the Hawaiian Islands have never been

Second World War than in calling for women to return to domestic life after the war. Since the Hawaiian Islands have never been

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问题 Second World War than in calling for women to return to domestic life after the war.
Since the Hawaiian Islands have never been connected to other land masses, the great variety of plants in Hawaii must be a result of the long-distance dispersal of seeds, a process that requires both a method of transport and an equivalence between the ecol-line ogy of the source area and that of the recipient area. 5 There is some dispute about the method of transport involved. Some biologists argue that ocean and air currents are responsible for the transport of plant seeds to Hawaii. Yet the results of flotation experiments and the low temperatures of air currents cast doubt on these hypotheses. More probable is bird transport, either externally, by accidental attachment of the seeds to feathers, or internally, by the swallowing of 10 fruit and subsequent excretion of the seeds. While it is likely that fewer varieties of plant seeds have reached Hawaii externally than internally, more varieties are known to be adapted to external than to internal transport.
The author mentions the results of flotation experiments on plant seeds(lines 7-8)most probably in order to
选项 A、support the claim that the distribution of plants in Hawaii is the result of the long-distance dispersal of seeds
B、lend credibility to the thesis that air currents provide a method of transport for plant seeds to Hawaii
C、suggest that the long-distance dispersal of seeds is a process that requires long periods of time
D、challenge the claim that ocean currents are responsible for the transport of plant seeds to Hawaii
E、refute the claim that Hawaiian flora evolved independently from flora in other parts of the world
答案D
解析 This question asks why the author mentions flotation experiments. Flotation experiments are mentioned in the passage in order to show that some evidence casts doubt on the claim that ocean currents were the means by which seeds were transported to Hawaii. Thus, Choice D is correct. Choice A is incorrect since the claim that plant distribution in Hawaii is the result of long-distance dispersal of seeds is a given in the passage, not an idea that the author feels a need to substantiate. Choice B is eliminable since the flotation experiments are introduced at a point where the author is challenging, rather than lending credibility to, the air current hypothesis and because flotation experiments would more likely reflect on ocean currents than air currents. Choice C is eliminable since the passage does not address the length of time required for longdistance seed dispersal. Finally, Choice E is eliminable since it too describes an idea that is not discussed in the passage.
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