单项选择题
A.the lifting appliance can always lift the freight within its rated load
B.attention should be paid in order not to break the wedge when lifting cargo
C.sometimes the lifting work needs other assistance other than the lifting appliance
D.lifting work should be done with every part fit, tightness or adhesion
单项选择题 In order to remove the carbon deposit from the threaded recess, we can use（）
单项选择题 Waste oil should（）
单项选择题 All items such as steam pipes, exhaust pipes and fittings which, because of their location and operating temperature, present a hazard should be adequately lagged.That means the items should（）