单项选择题
The main function of the core of a wire rope is to（）.
A.give flexibility B.support the strands laid around it C.allow some circulation around the strands D.allow lubrication inside the rope
单项选择题 Neglecting friction，you desire to lift a 300 kgs weight with a stress on the hauling part of 100 kgs.Which of the following tackles would you use?（）.
单项选择题 Manila slings should not be used to load（）.
单项选择题 Manila lines in which the strands are right-hand laid（）.
