观察员

例句：

1. 1.The scientist is an observer of the experiment.
   这位科学家是实验的观察者。
2. 2.He is an excellent observer and always records his observations.
   他是一位优秀的观察者，总是记录他的观察。
3. 3. The teacher asked the students to observe the changes in the weather.
   老师要求学生们观察天气的变化。