题目

阅读理解 Researchers found brushing your teeth three or more times per day is linked with lower risk of heart failure and atrial fibrillation—a heart condition that causes an irregular and often abnormally fast heart rate. One possible theory behind the discovery is that frequent tooth brushing reduces bacteria living in the pocket between the teeth and gums, preventing it from entering the blood stream. Existing studies show poor oral hygiene(口腔卫生) leads to bacteria in the blood, causing inflammation(炎症) in the body. Inflammation increases the risks of irregular heartbeat and heart failure, where the heart's ability to pump blood or relax and fill with blood is weakened. In their new research, scientists in South Korea examined the connection between oral hygiene and occurrence of these two conditions in a series of studies of more than 161,000 participants aged between 40 and 79. Participants underwent a routine medical examination between 2003 and 2004 and information was collected on height, weight, laboratory tests, illnesses, lifestyle, oral health, and oral hygiene behaviors. During a follow-up of ten and a half years on average, three percent of participants developed atrial fibrillation and around five percent developed heart failure. The lead investigator of the new study is Tae-Jin Song, a doctor and professor at Mokdong Hospital at Ewha Womans University in Seoul, South Korea, said: "We studied a large group over a long period, which adds strength to our findings." But he also noted that the analysis was limited to one country and as an observational study does not prove causation. An accompanying editorial states: "It is certainly too early to recommend tooth brushing for the prevention of atrial fibrillation and congestive heart failure. While the role of inflammation in the occurrence of heart and blood vessels' disease is becoming more and more evident, further studies are needed to explain strategies of public health importance." （1） Which is true about frequent tooth brushing? A . It reduces the risk of heart failure. B . It promotes the heart beat faster. C . It rids the bloodstream of bacteria. D . It weakens the hearts' ability to pump blood. （2） What does the underlined part "these two conditions" in paragraph 3 refer to? A . Inflammation and bacteria. B . Heart failure and atrial fibrillation. C . Oral hygiene and occurrence of heart failure. D . The heart's ability to pump blood or relax and fill with blood. （3） It can be inferred that the outcome of the research      . A . is discouraging. B . has its limit. C . has its variety. D . is unexpected. （4） From which is this text probably taken? A . A magazine. B . A diary. C . A guidebook. D . A novel. 答案： A B B A

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