食品生产车间窗台应距地面多少米以上（）
A.3m
B.1.5m2
C.1／100～1／50
D.1.0m
E.1.5m
参考答案：D
With his son _____, the old man felt unhappy.
A．to disappoint
B．to be disappointed
C．disappointing
D．being disappointed
简述控制和调节螺杆式压缩机润滑油系统的注意事项？
