单选题 Each one of us who ______ now living is destined to witness remarkable scientific discoveries.
A. is B. are C. have being D. Were

【正确答案】 B
【答案解析】根据题意，who引导一定语从句，其谓语动词的性数应与定语从句所修饰的先行词取得一致。根据题意，who引导的定语从句的先行词为us，因此A可排除。根据定语从句中now一词，C和D可以排除，B为正确选择。