I. ClozeIn this part, a passage is given with ten blanks. You are required to select oneword for each blank from a list of choices in the word bank. Read the passagecarefully before making your choices. You may not use any of the words in thebank more than once.
A. raising B. risk C. physiologically D. effect E. mentallyF. distinct G. average H. constant
I. adds J. pregnantK. educating L. suppress M. nerves N. relative O. adapts
Mothers who have complained through the centuries that their sons will be thedeath of them may be right — a study published in the journal Science shows havingboys shortens a woman’s life span. Each son takes a(n) 1_______ of 34 weeks off awoman’s life span, evolutionary biologist Samuli Helle and colleagues at theUniversity of Turku found. On the other hand, having daughters 2_______, but onlyvery slightly, to a woman’s life span. Helle and colleagues looked at birth and marriage records of Sami People（居住在北欧拉普兰地区的人） from 1640 to 1870. “Our results suggest that giving birth tosons had a higher 3_______ long-term survival cost for mothers than giving birth toand 4_______ daughters,” they wrote. There could be biological reasons for this.Studies show boys are 5_______ more demanding to produce — they grow biggerand faster in the womb（子宫）, and some studies show it takes a woman longer toget 6_______ again after having a son than after having a daughter. Testosterone（睾丸激素） produced by the fetus（胎儿） could 7_______ the mother’s immune（免疫的） system and perhaps make her more reliable（易受影响的）to disease. Therecould be genetic or social differences among the Sami, who are 8_______ from theirFinnish and Swedish neighbors, Helle said. But he does not think so. “There is noreason to believe that this 9_______ would be only visible in Sami people,” he said.“Generally, boys get on their mother’s 10_______ more than girls because they arerunning around. On the other hand girls are more willing to help their mothers.”
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