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
参考答案：D
Between the shop and the library _________ an apple tree _________ some apples. [ ]
A. is; with
B. are; has
C. is; has
D. are; with
属于急性上感引起的并发症有
A．中耳炎
B．风湿热
C．咽后壁脓肿
D．肺炎
E．支气管炎
