单选题 Tom will never forget these days ______ he traveled in China with his mother, ______ has a great effect on his life.

【正确答案】 B

【答案解析】[解析] 本题前一空考查的是引导限制性的定语从句的关系副词，表示时间要用when；后一空考查的是引导非限制性的定语从句的关系代词，用which指代主句中定语从句的内容，并在从句中作主语。