传声器频率响应曲线在高频段有“上翘”时，声音会显得( )。

A．浑厚

B．丰满

C．明亮

D．柔和

Each lifebuoy shall be marked in block capitals of the Roman alphabet with（）of the ship.

A.the call sign and name

B.the official number and name

C.the port of registry and name

D.the port of registry and official number