A - After each surgery 每台手术之后
B - Whenever the fill volume is below 50% 读数在50%以下的任何时候
C - When the CO2 absorbent granules are completely purple 当二氧化碳吸收罐内的颗粒完全变成紫色的时候
D - When the fewest people are in the clinic 诊所内人最少的时候
E - Depends on the type of breathing circuit 根据不同呼吸回路决定