A . check and regulate the water level
B . close the air cock once fires are lit
C . blowdown the gage glass
D . crack the steam stop to assure protective steam flow
[单选题]People in Beijingwear a lot of clothing during winter to fend(抵御)off the co
[单选题]People in Beijingwear a lot of clothing during winter to fend(抵御)off the co
[单选题]People in Beijingwear a lot of clothing during winter to fend(抵御)off the co
[单选题]People in Beijingwear a lot of clothing during winter to fend(抵御)off the co
[单选题]People in Beijingwear a lot of clothing during winter to fend(抵御)off the co
[单选题]People in Beijingwear a lot of clothing during winter to fend(抵御)off the co
[单选题]People in Beijingwear a lot of clothing during winter to fend(抵御)off the co
[单选题]People in Beijingwear a lot of clothing during winter to fend(抵御)off the co
[单选题]People in Beijingwear a lot of clothing during winter to fend(抵御)off the co
[单选题]People in Beijingwear a lot of clothing during winter to fend(抵御)off the co