在使用天平前，请确保它已经归零。

Please ensure the balance is properly ___zeroed before use.

侦探全神贯注地盯着监控画面，试图找出线索。

The detective ___zeroed in on the surveillance footage, searching for clues.

每次实验结束后，我们都要将仪器读数归零。

After each experiment, we need to have the instrument readings ___zeroed.