随便翻了一下,有几道题有疑问.请大家帮忙解释一下. when amphibians first appeared on Earth millions of years ago,the amount of ultraviolet radiation penetrating Earth's atmosphere was much greater than it is today.Therefore,current dramatic increases in amphibian populations cannot be the result of recent increases in ultraviolet radiation penetrating Earth's atmosphere. which is an assumption on which the argument depends? A the eggs of modern amphibians are not significantly more vulnerable to ultraviolet radiation than the eggs of the first amphibians were. B Modern amphibians are not as likely as the first amphibians were to live in habitats that shield them from ultraviolet radiation. C Populations of modern amphibians are not able to adapt to changing levels of radiation as readily as populations of early amphibians were. D The skin of amphibians is greatly more sensitive to ultraviolet radiation than the skin of other animals is . E the skin of amphibians is less sensitive to ultraviolet radiation than to other types of radiation. 请大家对给出的答案分析一下.谢了先 |