center的形容词形式是什么

　　We've converted from oil to gas central heating.

　　我们已经把中央供热系统由燃油改成了燃气。

　　He crossed the street and walked alongside Central Park.

　　他过了马路，然后在中央公园旁边走着。

　　The traffic lights are controlled by a central computer.

　　交通信号灯由中心计算机控制。