古代农业文明观察星星并用来观测记录季节变化。

Ancient agricultural civilizations observed the stars and then used those observations to keep track of the seasons.

youdao

给它安装无线电设备是很困难的，而且仅凭肉眼观测也太不可靠，无法对它的行为进行确切的观察。

Attaching radio devices to it is difficult, and visual sightings are too unreliable to give real insight into its behavior.

youdao

由于每个国家只有一个观测结果，因此不可能控制各国间未观察到的异质性。

With only one observation per country, it is impossible to control for unobserved heterogeneity across countries.

youdao

And the second thing is that the observer is part of the observation through that interaction.

第二件事是观测者,是内部反应的观察资料的一部分。

麻省理工公开课 - 固态化学导论课程节选