A casual observer would have taken them to be three men out for an evening stroll.

乍一看会以为这三个男人是晚上出来闲逛的。

He argues that truly objective science is impossible: the observer affects the system he or she observes.

他争辩说完全客观的科学是不存在的：观察者会对其观察的系统产生影响。

Observers say the events of the weekend seem to have increased support for the opposition.

观察家们说周末事件似乎加大了对反对派的支持。

The president suggested that a UN observer should attend the conference.

主席建议应该有一名联合国观察员参加该会议。