单项选择题
The use of（）between bags may lead to chafe and tearing of the bags.
A.strips of burlap B.heavy paper C.dunnage boards D.strips of rope yarn
单项选择题 The tackle that raises and lowers the boom is（）.
单项选择题 The strongest of the natural fiber ropes is（）.
单项选择题 The square knot is used for（）.
