填空题 Overhead railway, (whose) tracks (are elevated out of) the way of surface traffic, (might have been) (one possible solution to) heavy traffic in big cities. A. whose B. are elevated out of C. might have been D. one possible solution to
  • 1、
【正确答案】 1、C    
【答案解析】改为might be。might be此处表示可能性；might have done是对过去发生的事情的肯定猜测。