单项选择题 Which of the following items is necessary for all waste heat boiler installations, regardless of design or manufacturer? （）

单项选择题 Prior to lighting off a cold automatically fired auxiliary boiler, yon should （）.

单项选择题 After a normal, or safety shutdown, automatic combustion control systems for an auxiliary boiler are designed to prevent the immediate re-firing of a burner in order for the （）.