带式输送机道设置防灭火水管间隔()设1个管接头和阀门。
A.20m
B.30m
C.40m
D.50m
参考答案:D
— Do you know Mozart?
— Of course. He wrote _____ of beautiful pieces of music.
A.hundred
B.a hundred
C.hundreds
D.six hundred
食管癌好发部位是()
A.胸部食管上段
B.颈部食管
C.胸部食管中段
D.胸部食管下段
E.腹部食管