单项选择题
A.temporary guide base B.permanent guide base C.guide frame D.foundation template
A.syphon barometer B.cistern barometer C.aneroid barometer D.fortin barometer
A.a heavy anchor with an extra long line used to anchor in deep water B.a cone shaped bag used to slow down the wind drift effect C.a pad eye to which the sea painter is made fast D.made of wood if it is of an approved type