Which of the following is a characteristic of a Ro-Ro vessel（）.

A.Passenger tours available upon docking

B.Long port stays necessary to secure vehicles

C.Short in port turnaround times

D.Heavy vehicles only require lightweight securing equipment

刻画人物和表现环境的主要光线是指（）。

A、主光

B、正面光

C、侧光

D、逆光