单项选择题
A．famous B．forgotten C．strange D．unknown
A．a hovercraft can not fly high because of the surrounding high-pressure air B．a hovercraft is as much in use as a plane C．a hovercraft "flies" with a greater speed than ships D．a hovercraft also has the problem of wave resistance
A．hell B．place of great heat and fire C．furnace for smelting iron D．fireball