— _____!
— It's OK. [ ]
A. I'm sorry
B. Hi
C. Watch out
答案：A
Everyone should do something ______ wild animals.
A．to protect
B．protecting
C．protect
D．to protecting
凡经常检修的部位应设可靠的隔断装置，下列设备（）为可靠的隔断装置。
A.插板阀
B.闸阀
C.蝶阀
D.水封
