单选题 As a policeman, Mr. Brown thought that he had a duty to ______ the lost children in finding their homes.

【正确答案】 A

【答案解析】[考点] 动词搭配
[解析] assist“协助”，用于句型assist sb. in doing sth.；help“帮助”；provide“供给，提供”；support“支援，帮助支持”。