99色精品-9色在线-99色在线-99色视频 国产欧美日产一区二区三区_亚洲精品亚洲人成在线观看_四虎在线精品永久观看_免费一级a一片久久精

單項(xiàng)選擇題

Which of the following precautions must be taken if an electric immersion heater is used to keep the coolant in a diesel engine warm during the time the engine is secured?()

A.The coolant temperature must be maintained at 180℃
B.The thermostatic bypass valves must be manually opened before the engine is started
C.The pressure cap must be removed while the engine is secured
D.Electrical power to the heater must be secured before the cooling system is drained

微信掃碼免費(fèi)搜題