survey of existing tracks

例句：

1. 1.The survey team will conduct a thorough investigation of the area.
   调查团队将对该地区进行彻底的调查。
2. 2.The survey results were published in the journal last month.
   上个月，调查结果在期刊上发表。
3. 3.The survey revealed that the population was growing at a rate of 2% per year.
   调查发现人口每年以2%的速度增长。