恶性度最高的甲状腺癌为（）
A. * * 状腺癌
B.髓样癌
C.滤泡状癌
D.未分化癌
E.腺瘤癌变
参考答案：D
对肛门括约功能起着主要作用的肌肉是（）
A.内括约肌
B.外括约肌皮下环
C.外括约肌浅环
D.外括约肌深环
E.以上均是
Usually in winter there's _____ ice in the north. [ ]
A. few
B. many
C. too much
D. much too
