2. 考研
  3. Mammals vary enormously in size, from weighing less than a penny to measuring more than three school buses in length. Some group

Mammals vary enormously in size, from weighing less than a penny to measuring more than three school buses in length. Some group

admin2017-08-11  23
问题     Mammals vary enormously in size, from weighing less than a penny to measuring more than three school buses in length. Some groups of mammals have become very large, such as elephants and whales,【C1】______others have always been small, like primates. A new theory developed by an international team, led by Jordan Okie,【C2】______an explanation for why and how【C3】______groups of organisms are able to evolve【C4】______sizes, whereas others are not.
    The research team【C5】______information on how quickly an individual animal grows and used it to【C6】______how large it may get【C7】______evolutionary time. Their research was published recently.
    The new theory developed from the observation that some animals【C8】______fast and die young, while others take their time and mature much later. "Fast" animals-such as mice—breed very quickly, while humans mature slowly and are relatively older when they first have children. The theory【C9】______that those species that are relatively faster are more likely to evolve a large size quicker than slow species, and that their maximum size will be greater.
    The research team tested their theory using the【C10】______records of mammals over the last 70 million years, examining the maximum size of each mammal group【C11】______that time, including whales, elephants, seals and primates. They found that their theory was very well【C12】______.
    "Primates have evolved very slowly, and never got bigger than 1,000 pounds," said Okie, "The【C13】______was true of whales, which evolved their large size at the fastest【C14】______recorded."
    The theory also makes predictions about the relative risks of extinction for large animals【C15】______small. The maximum size of an animal is limited by the rate of mortality in the【C16】______. Because larger animals【C17】______breed less frequently than smaller animals,【C18】______the mortality rate doubles, the maximum size is predicted to be 16 times smaller.
    "This is a really surprising【C19】______," said Okie. "It points to another reason why many of the large animals went【C20】______after the last Ice Age, and their high risk of extinction in modern environments."
【C18】
选项 A、in that
B、despite
C、therefore
D、if
答案D
解析 从句指出死亡率提高一倍(the mortality rate doubles)，主句表明预计(is predicted to be)该动物的最大体型就会缩小16倍。从语义上可判断前半句为后半句的条件。故选D项if“如果”。
转载请注明原文地址:https://jikaoti.com/ti/Hpr7FFFM
0

考研英语一

相关试题推荐
随机试题
最新回复(0)