成人择期手术前应禁食（）。
A．1～2小时
B．2～3小时
C．2～4小时
D．4～8小时
E．8～12小时
参考答案：E
Tim had one of his legs broken when he fell off a ladder and has been ____ ever since. [ ]
A. badly off
B. well off
C. worse off
D. better off
下列哪些肺部疾病可引起纵隔向患侧移位()
A．肺不张
B．肺实变
C．肺水肿
D．肺发育不全
E．肺段隔离症
