7.21用英语怎么说

7.21 is a date and it can be written in English in a variety of ways. One way to write it is "July 21" or "07/21". Another way to write it is "7/21" if the month is understood or if the date is written in a context where the month is clear.
The origins of the date system used in the Western world, which includes the use of the months of the year and the division of the year into 365 days, can be traced back to the ancient Roman calendar. This calendar was later modified by the Catholic Church and adopted by many countries in Europe and around the world.
Here are some examples of how to use 7.21 in English sentences:
"I have a meeting on 7/21 at 2:00 PM." (In this sentence, the speaker is using the numeric version of the date to specify when the meeting is happening.)
"My birthday is on July 21st." (In this sentence, the speaker is using the month and ordinal number to indicate when their birthday is.)
"The deadline for the project is 7.21." (In this sentence, the speaker is using the numeric version of the date to specify when the deadline is.)
Here are the Chinese translations for these sentences:
"我7/21下午2点有个会议。"
"我的生日是7月21日。"
"项目的最后期限是7.21。"