50. The writer believes that instant messaging is

　　.

　　A. full of fun but time-consuming

　　B. widespread but unnecessary

　　C. quick but difficult to do

　　D. common, used and cheap

　　51. Which might be the main idea of the passage?

　　A. Who can escape QQ and cell phone text messaging?

　　B. Why is instant messaging so popular?

　　C. Chatting online is good for your typing skill.

　　D. Chatting on QQ is natural for people.

　　E

　　Scientists at Harvard University and Bates College find female chimpanzees (黑猩猩) appear to treat sticks as dollscarrying them around until they have children of their own. Young males engage in such behavior much less frequently.

　　The new work by Sonya M. Kahlenberg and Richard W. Wrangham, described this week in the journal Current Biology, provides the first evidence of a wild non­human species playing with dolls, as well as the first known sex difference in a wild animal’s choice of playthings.

　　The two researchers say their work adds to a growing body of evidence that human children are probably born with their own ideas of how they want to behave, rather than simply mirroring other girls who play with dolls and boys who play with trucks. Doll play among humans could have its origins in object—carrying by earlier apes (猿类), they say, suggesting that toy selection is probably not due entirely to socialization.

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