Old people must be politelyA. spoken toB. speak toC. pokenD. spoke

问题补充：

Old people must be politely

A. spoken to

B. speak to

C. poken

D. spoke

答案：

(答案→)A. spoken to

B. speak to

C. poken

D. spoke

解析：被动语态中句子主语和谓语动词是动宾关系，句意：必须礼貌的对老年人说话。可知老人是说话的对象，故用被动语态，选A。