上午用英语怎么说A.M.

"A.M." stands for "Ante Meridian" which means "before noon" in Latin. It is commonly used to refer to the morning time period from midnight to noon.

Here are some examples of how to use "A.M." in a sentence:

"I have a meeting at 9 A.M." (我早上9点有个会议。)
"The store opens at 10 A.M." (商店早上10点开门。)
"I usually wake up at 6 A.M." (我通常早上6点醒来。)

Note: In writing, "A.M." is usually written in uppercase letters and with periods after each letter.