The law says that all public buildings must be accessible to people who have trouble .A. w

问题补充：

The law says that all public buildings must be accessible to people who have trouble .

A. walking

B. walk

C. to walk

D. walked

答案：

(答案→)A. walking

B. walk

C. to walk

D. walked

解析：考查固定句式。固定搭配have some trouble (in) doing sth做某事有困难；句意：法律规定，所有的公共建筑都要让那些步行有困难的人很容易就进入了。故A正确。