But it’s unlikely you’ll be able to survey the WHOLE population.

但是你不太可能调查整个人群。

If I survey three people who are going to vote for president, I clearly haven't surveyed the entire population.

如果我调查三个要投票给总统的人，我显然没有调查全部人口。

The plan is for drones to eventually be able to survey populations for disease by reading the blood oxygen levels of humans from the air.

该计划是让无人机最终能够通过从空气中读取人类的血氧水平来调查人群的疾病。