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 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 of the passage is primarily concerned with ______.
A.discussing different approaches biologists have taken to testing theories about the distribution of plants in Hawaii
B.discussing different theories about the transport of plant seeds to Hawaii
C.discussing the extent to which air currents are responsible for the dispersal of plant seeds to Hawaii
D.resolving a dispute about the adaptability of' plant seeds to bird transport
第5题
丹毒的临床特点,下列不正确的是
A、起病急
B、病变处皮肤鲜红
C、一般不化脓
D、下肢丹毒可致橡皮肿
E、病变部位与周围皮肤界限不清
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