单项选择题
The safety valves should be tested and adjusted when the boiler survey is （）
A.completed B.carried out C.cleaned D.steamed
单项选择题 A donkey boiler is （）.
单项选择题 Safety valves on a boiler vent to the （）.
单项选择题 The boiler feed pump discharge pressure is higher than the steam drum pressure to （）.
