First of all, be careful.

首先，小心。

First of all, you must stop worrying!

首先，你必须停止担心！

First of all, he is very tall and handsome.

首先，他非常高大和英俊。

First of all, find out what's wrong with him.

首先，找出他出了什么问题。

First of all, our instructors showed us the safety equipment.

首先，我们的教练向我们展示了安全设备。

First of all, let me introduce my friend Lily to you.

首先，让我向你介绍我的朋友莉莉。

First of all, come and look in the lost and found box!

首先，来看一下失物招领箱！

First of all, I never realised working in a barber's was so tiring.

首先，我从未意识到在理发店工作是如此累人。

May Day is on the first of May each year.

五一劳动节是每年五月一日。

The rent is due on the first of every month.

租金每月一号到期。