Paul always goes to the center of the city .A. on bike B. take a bus C. on feet D. by car

问题补充：

Paul always goes to the center of the city .

A. on bike

B. take a bus

C. on feet

D. by car

答案：

A. on bike

B. take a bus

C. on feet

(答案→)D. by car

解析：句意：葆罗总是坐车去市中心。“乘坐交通工具去做某事”即“do sth by bike/car/bus/boat/on foot”，注意需要交通工具使用单数形式，所以on feet表达错误，take a bus在句中做谓语；故选D。