Walking together, my father and I used to have a lot of conversations_______ I learned lessons from his experience. A.that B.where C.when D.through which 答案:D 考查定语从句。介词加关系代词的用法。本句中介词的选择来自于句意,表示通过某种方式。 20.电火花打点计时器使用交流电源(填“直流”或“交流”),工作电压220V.电磁打点计时器使用交流电源(填“直流”或“交流”).