单选题 They ______ oiled paper umbrellas for more than 400 years.
  • A. have been making
  • B. had been making
  • C. was making
  • D. had made
【正确答案】 A
【答案解析】[解析] 本题考查现在完成进行时态。从时间状语for mom San 400 years判断，动作或状态从过去的某时开始，一直持续到现在，可能还会继续下去。所以，本题答案是选项A。