to watch carefully the way something happens or the way someone does something, especially in order to learn more about it

The role of scientists is to observe and describe the world, not to try to control it. 科学家的任务是观察和描述这个世界，而不是试图控制它。

[ + question word ] He spent a year in the jungle, observing how deforestation is affecting local tribes. 他在丛林里住了一年，考察滥伐森林对当地部落造成了何种影响。

Children learn by observing adults. 儿童通过观察成年人来学习。

to notice or see

Jack observed a look of anxiety on his brother's face. 杰克注意到了他哥哥脸上焦急的神情。

[ + question word ] The guards failed to observe who delivered the package. 卫兵没有注意到是谁递送的这个包裹。

[ + that ] In all these films one observes that directors are taking a new interest in Native American culture. 在所有这些电影中，人们发现导演们对美国本土文化产生了新的兴趣。

[ + infinitive without to ] A teacher observed her climb over the gate. 有位老师看到她翻过大门。

to make a remark about something

[ + speech ] "I've always found German cars very reliable," he observed. “我一直认为德国汽车很可靠，”他说道。

[ + that ] She observed that it would soon be time to stop for lunch. 她说很快就到停下来吃午饭的时间了。

to obey a law, rule, or custom

People must observe the law. Nobody should be an exception. 人们必须遵纪守法，谁都不应该例外。

The old people in the village still observe the local traditions. 村里的老人仍然遵守当地的传统。

Do you observe Passover? 你们过逾越节吗？