单项选择题
An example of a modern anchor which has a stock is a(n)（）.
A.articulated anchor B.Flipper Delta anchor C.Baldt anchor D.Danforth anchor
单项选择题 An example of a messenger is a（）.
单项选择题 All electrical appliances aboard a vessel should be grounded to（）.
单项选择题 All echo-sounders can measure the（）.
