单项选择题
A.incorrect electrode setting
B.incorrect nozzle position
C.clogged fuel nozzle
D.broken high tension lead
单项选择题 In the event of a flame failure in an auxiliary water-tube boiler, you must（）
单项选择题 The purpose of a temperature sensing device installed in the stack of a small automatically fired auxiliary steam boiler is to secure the oil burner（）
单项选择题 Burner ignition failure in an automatically fired auxiliary boiler would be caused by（）