approximate straight-line mechanism

例句：

1. 1.The distance between the two cities is approximately 500 kilometers.
   两座城市之间的距离大约是500公里。
2. 2.The temperature in this area is approximately 20 degrees Celsius.
   这个地区的温度大约是20摄氏度。
3. 3. The data we have is approximately accurate to within a few percent.
   我们拥有的数据大约准确度在百分之几以内。