We've converted from oil to gas central heating.

　　我們已經(jīng)把中央供熱系統(tǒng)由燃油改成了燃氣。

　　He crossed the street and walked alongside Central Park.

　　他過了馬路，然后在中央公園旁邊走著。

　　The traffic lights are controlled by a central computer.

　　交通信號燈由中心計算機控制。