单项选择题
The irregular black line around a charted light such as Race Rock Light indicates that it is （）.
A.unwatched B.surrounded by riprap C.a minor light D.constructed on an artificial island
单项选择题 The horizontal flat surfaces where the upper stock joins the rudder are the（）.
单项选择题 The grip of a joint represents the（）.
单项选择题 The fluke angle of an anchor system is the angle between the（）.
