10个月男孩，呕吐、腹泻5天，伴高热（39.0℃）大便5~6次/日，初为水样便，随即为黏冻状大便，偶带血，量不多，体检：轻度脱水貌，心肺腹未见异常，大便常规：黏液便，白细胞15~20/高倍镜，偶见吞噬细胞，连续大便培养两次未见痢疾杆菌，该婴儿腹泻最大可能的病因是：（）
A.产毒性大肠杆菌
B.阿米巴
C.埃可病毒
D.鞭毛虫
E.侵袭性大肠杆菌
参考答案：E
 A new study has found no evidence that sunscreen, commonly used to reduce the risk of skin caner, actually increases the risk.Researchers from the University of Yale based their findings on a review of 18 earlier studies that looked at the association between sunscreen use and melanomas (黑素瘤). They said that they found flaws in studies that had reported associations between sunscreen use and higher risk of melanoma.Most health experts believe that by protecting the skin from the harmful effects of the sun, sunscreen helps prevent skin cancer, which is increasing in incidence (发生率) faster than any other cancer in the United States.But questions have been raised about sunscreen and whether it may have the opposite effect, perhaps by allowing people to remain exposed to the sun longer without burning.The researchers said that among the problems with some earlier studies is that they often failed to take into account that those people most at risk for skin cancer—people with fair skin and freckles (雀斑), for example—are more likely to use sunscreen. As a result, it may appear that sunscreen users get cancer more often.The studies, which generally relied on volunteers to recall their sunscreen use, were also unable to prove how well the products had been applied, said the new study.小题1:The underlined word “flaws” in the 2nd paragraph most probably means .
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ed the effect of sunscreen