在三月用英语可以说 "in March."

来源：这是一个基本的英文表达，根据英文月份的命名方式，每个月份都可以在前面加上介词 "in" 表示。

例句：

I will be traveling to Europe in March.

The cherry blossoms are expected to bloom in March.

The deadline for the project is in March, so we need to make sure we're on track.