单选题 During the rush hours, a policeman directs traffic at the intersection, and ______ there have been no accidents.
  • A. as of now
  • B. to the present
  • C. up until currently
  • D. so far
【正确答案】 D
【答案解析】[解析] 此题考查副词短语的区别。 [详细解答] 副词短语可用来表示时间、地点、程度等概念。so far常用于完成时态。因此D为正确选项。