单选题 He studied hard at school when he was young, ______ contributes to his success in later life.

【正确答案】 A

【答案解析】[解析] 本题考查非限制性定语从句的用法。本句后半句为非限制性定语从句，which指代前半句话。非限制性定语从句只能用which，as引导。句意：他年轻时在学校学习很努力，这为他以后的成功铺垫了道路。