approximation with restricted range

例句：

1. 1. Thedistance between the two cities is approximately50 miles.
   两座城市之间的距离大约是50英里。
2. 2. He estimated the time itwould take to finish the project at threehours.
   他估计完成这个项目需要三个小时。
3. 3.The company's financial performance is anapproximation of its long-term success.
   公司的财务表现可以作为其长期成功的一种近似。