上午用英语怎么说?

"上午" in English is "morning" or "a.m.".

"Morning" comes from the Middle English "morwening" which means the time from midnight to noon. The abbreviation "a.m." is from the Latin "ante meridiem" which means "before midday".

Example sentences:

Good morning!
I usually have breakfast at 7 a.m.

中文翻译：

早上好！
我通常在早上7点吃早餐。