单项选择题
The strongest of the natural fiber ropes is（）.
A.Nylon B.Dacron C.Manila D.Sisal
单项选择题 The square knot is used for（）.
单项选择题 The rope which is rove from the truck to be used with a bos’n chair is called a（）.
单项选择题 The rolling hitch could be used to（）．
