下列不是青春期所具有的生理特点的是（　　）

A．身体开始发胖

B．男孩出现遗精

C．女孩出现月经

D．身高突然增加

In the cross-lake swimming race, a boat will be ____in case of an emergency.

A．standing by

B．turning on

C．getting on

D．running on