在白天用英语怎么说

在白天用英语可以说作 "in the daytime" 或 "during the day"。这两个词都表示在白天的时间，具体来源可能是源于英语中 daylight 这个词，表示阳光照耀的时间。

例句：

I usually go for a walk in the daytime.
We have a lot of work to do during the day.
I prefer to do outdoor activities in the daytime when it's sunny.
During the day, the temperature is usually warmer than at night.