氟利昂油分离器设有（）的自动回油装置。
A.浮球阀
B.手动直角阀
C.电磁阀
D.液位阀
参考答案：A
机械式经纱保护装置，按作用时钢筘状态的不同可分为游筘式、（）和联合式三种护经装置。
After 5 days of fantastic space trip ,the two astronauts walked out of the spaceship, ______.
A．tired and happy
B．tired but happy
C．tiredly and happily
D．tiredly but happily
