問題詳情

B.A large study offers more evidence of a link between traumatic brain injuries and dementia later in life, with repeatedinjuries and severe ones posing the greatest danger. Researchers analyzed 36 years of health records of 2.8 million people inDenmark, where a national health system makes it possible to explore connections in a far-reaching way. ___21____ the riskwas small. About 95 percent of people who suffered a brain injury never developed dementia. But a single severe brain injuryincreased the risk of later dementia by 35 percent ___22___ a person who never had brain trauma. A mild brain injury increasedthe risk by 17 percent. Each additional brain injury added to the danger.  Scientists know that a blow to the head can damage brain cells, but they don't know exactly ___23___that might lead tolater cognitive problems. This kind of study can't prove a cause-and-effect relationship, but researchers tried to eliminate thepossible effects of age, gender, marital status and health, including depression. In a commentary in the journal, Dr. CarolBrayne of University of Cambridge's medical school in England wrote that improvements in care mean more people aresurviving brain injuries, making it crucial to understand more about their long-term effects.
21.
(A) Therefore
(B) Overall
(C) Instead
(D) On the contrary

參考答案

答案：B
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

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