All the copper bars are（）different sizes.

A.two black balls in a vertical line
B.three black balls in a vertical line
C.three shapes in a vertical line； the highest and lowest shall be red balls and the middle a white diamond
D.three black shapes in a vertical line； the highest and lowest shall be balls and the middle one a diamond

A.a vessel restricted in her ability to maneuver
B.a vessel engaged in laying，serving or picking up a navigation mark，submarine cable or pipeline
C.a vessel not under command
D.a power-driven vessel

A.store fluid under pressure
B.act as a fluid reservoir
C.provide overpressure relief
D.replenish fluid to a system