___________ books do you have?[ ]
A. How much
B. How are
C. What's
D. How many
答案:D
机械性肠梗阻的原因是
A.肠腔堵塞
B.肠管受压
C.肠壁病变
D.肠管缺血
E.肠管膨胀
下述哪个系统的工作与气源系统无关()?
A、机翼和发动机热防冰
B、液压油箱增压
C、水箱增压
D、燃油箱增压