第2题: [单项选择]{{I}} Questions 11-13 are based on the following passage about education in the United States. You now have 15 seconds to read Questions 11-13.{{/I}}At what age do most children start school A. At 7. B. At 6. C. At 5. D. At 8. 参考答案:B
第21题: [单项选择]关于胎儿肛门闭锁的超声表现,正确的是() A. 单泡征 B. 胎儿上腹部双泡征 C. 近端小肠显著扩张 D. 胎儿骨盆断面“双叶”形囊性肿物 E. 胎儿胃泡不显示 参考答案:D 答案解析:肛门闭锁时,常在胎儿盆腔下部显示出“V”形或“U”形扩张的肠管。未检出肠管扩张,不能除外肛门闭锁的可能,产前超声诊断缺乏特异性。