It is necessary to find a new home for people in space.

有必要在太空中为人类找到新家园。

Sometimes it is necessary to say no.

有时候说不也是必要的。

It is necessary to drink water every day.

每天喝水是必要的。

I think it is necessary to recheck this data.

我认为有必要重新检查这些数据。

It is necessary to check your email regularly.

定期检查你的电子邮件是必要的。

In this situation, it is necessary to take action.

在这种情况下，有必要采取行动。

In court, it is necessary to prove the suspect's crime.

法庭上需要求证嫌疑人的罪行。

In this weather, it is necessary to wear thick clothes.

在这种天气下，有必要穿厚衣服。

For safety reasons, it is necessary to install a firewall.

为了安全起见，有必要安装防火墙。

It is necessary to control reverberation during recording.

录音时需要控制混响。