We have to observe carefully what's going on there.

　　我們必須仔細觀察那里的動靜。

　　He made a telescope through which he could observe the stars.

　　他做了個望遠鏡,用其觀察星座。

　　All citizens should observe traffic rules.

　　每位公民都應該遵守交通規則。

　　We should observe the proprieties.

　　我們應該遵守禮節。

　　If they have to leave home, they must wear a face mask and observe good personal hygiene.

　　若外出,要佩戴口罩,注意個人衛生。