GMAT阅读历年真题练习下载六十.doc

GMAT阅读历年真题练习下载六十 GMAT阅读真题，对于考生来说，是非常珍贵的备考资料，所以GMAT资料下载的小编不辞辛苦为大家找到了这些资料，让我们快来做题吧！ 　　Until recently, scientists did not know of a close vertebrate analogue to the extreme form of altruism abserved in eusocial insects like ants and bees, whereby individuals cooperate, sometimes even sacrificing their own oppor( 5)tunities to survive and reproduce, for the good of others. 　　However, such a vertebrate society may exist among underground colonies of the highly social rodent Hydrocephalusgrabber, the naked mole rat. 　　A naked mole rat colony， like a beehive， wasp’s nest，or(10)termite mound，is ruled by its queen，or reproducing female. Other adult female mole rats neither ovulate nor breed. The queen of the largest member of the colony，and she maintains her breeding status through a mixture of behavioral and，presumably，chemical control. Queens have(15)been long-lived in captivity，and when they die or are removed from a colony one sees violent fighting for breeding status among the larger remaining females，leading to a takeover by a new queen. 　　Eusocial insect societies have rigid caste systems，each(20)insects’s role being defined by its behavior，body shape，and physiology. In naked mole rat societies，on the other hand，differences in behavior are related primarily to reproductive status (reproduction being limited to the queen and a few males)，body size，and perhaps age. Smaller nonbreeding(25)members，both male and female，seem to participate primarily in gathering food，transporting nest material，and tunneling. Larger nonreaders are active in defending the colony and perhaps in removing dirt from the tunnels. Jarvis’ work has suggested that differences in growth rates may influence the length of time that an individual performs(30)a task，regardless of its age. 　　Cooperative breeding has evolved many times in vertebrates，but unlike naked mole rats，most cooperatively breeding vertebrates(except the wild dog，Lycaon pictus)(35)are dominated by a pair of breeders rather than by a