The water level showing in a boiler water gauge glass is usually ( ) duringworking.

The water level showing in a boiler water gauge glass is usually ( ) duringworking.

A.higher than the actual drum water level

B.equal to the actual drum water level

C.increasing due to steam condensation in the glass

D.lower than actual drum wafer level

D解析：水位表上端通汽下端通水，温度不及炉内的高;炉内的炉水是水和汽泡的混合物，故其水位要高些。译文：锅炉运行期间，水位计显示的水位比炉内的实际水位低。