单项选择题 患儿男，9岁，3岁外斜。眼位：5m；-30△，向上25°；-40△，向下25°；-10△。确切的诊断应为（）A. 间歇性外斜视B. B.共同性外斜视C. C.外斜V征D. D.麻痹性外斜视E. E.先天性外斜视

单项选择题 基因突变和染色体变异的一个重要区别是（）

单项选择题 As with many large countries,the us has several distinct regions.Each region boasts its own special style of food.Visit the south and enj oy country-style cooking.Journey through Louisiana for some spicy Cajun cuisine；take a trip to New England and sample savory seafood dishes；travel through the midwest,"the breadbasket of the nation",for delicious baked goods；cruise over to the southwest and try some tasty Tex-Mex treats；finish your food tour in the Pacific Northwest with some gourmet coffee.