绞窄性小肠梗阻常见原因是()
A．肠内疝
B．肠扭转
C．肠套叠
D．肠粘连
E．以上都是
参考答案：E
75×80的末尾有______个零．
I wondered _____ the man was. [ ]
A. who
B. why
C. what
D. if
