On pacific islands, a newly arrived gecko species, the house gecko, is diplacing the previously established mourning gecko in urban area, but the populations of the two species are more stable in rural areas far from human settlement. The house gecko does not attack the mouring gecko, but in areas where insects congregate it prevents the mourning gecko from feeding on them. Which of the following contributes the most to explanation the difference between gecko population in urban and rural areas? a.In urban areas, geckos are value because they eat so many insects. b.Gecko defends teritorries against other members of the same species. c.House geckos that arrive on islands are carried there in boats and planes. d.In place where there are lighted buildings, insects tend to gather around the light. e.Mourning geckos are all females and reproduce asexually, but house gecko reproduce sexually. 官方答案是D,想不明白啊,明明是要求解释gecko城乡差异的,怎么扯到虫子喜好光上面去了……这个选项只是解释了insect为什么会congregate in an area,没有解释house gecko为什么会在这样的area里阻止mourning gecko进食啊。 open discussion
[此贴子已经被作者于2007-11-26 9:33:02编辑过] |