单项选择题
A term used to describe the dip in a towline that acts as a shock absorber is（）.
A.catenary B.step C.shock dip D.bight
单项选择题 A solution to overcome tripping defects is an arrangement of special plates on either side of the flukes，designed to set them in the correct tripping position. These special plates are called（）.
单项选择题 A shroud is（）.
单项选择题 A sheepshank is used to（）.
