下料前，凭经验进行划线，然后按着划线进行切割。
参考答案：错
简述消费者的权利和经营者的义务。
To prevent the spread of fire by conduction you should（）.
A.cool the bulkheads around the fire
B.remove combustibles from direct exposure
C.close all openings to the area
D.shut off all electric power
