单选题 Great as Russell was, many of his ideas ______ today and are being modified by the work of philosophers of our time.
  • [A] are to challenge
  • [B] may be challenged
  • [C] have been challenged
  • [D] ale challenging


【正确答案】 C
【答案解析】[解析] 时态语态题。根据逻辑关系首先可以确定应该为被动结构，排除选项[A]、[D]，又因为这一行为一直延续到现在，所以用现在完成时。正确答案为[C]