1
in September
表示月份时通常用介词in。
The school year starts in September.
学年在九月开始。
九月
先理解核心含义，再看它在真实句子里的用法。
九月
September
The school year starts in September.
学年在九月开始。
八月之后、十月之前的月份
the month following August and preceding October
My birthday is in September, so I usually celebrate it at the beginning of autumn.
我的生日在九月，所以我通常在初秋庆祝。
The new school year starts in September in many countries.
在许多国家，新学年于九月开始。
We are planning to travel to Japan this September, when the weather is still warm.
我们计划今年九月去日本旅行，那时天气还很暖和。
表示月份时通常用介词in。
The school year starts in September.
学年在九月开始。
表示具体某日时用介词on。
The meeting is on 15 September.
会议在九月十五日。
月份和年份连用时，通常用in，但年份前无介词时直接跟月份。
She was born in September 1990.
她出生于1990年九月。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
在九月
School starts in September.
学校在九月开学。
九月初
We plan to travel in early September.
我们计划九月初旅行。
九月末
The harvest begins in late September.
收获在九月末开始。
九月十一日
September 11th is a day of remembrance.
九月十一日是一个纪念日。
九月的天气
The September weather is usually mild.
九月的天气通常很温和。
九月的早晨
A cool September morning greeted us.
一个凉爽的九月早晨迎接了我们。
你还记得九月二十一的那个夜晚吗？
I love listening to 'September' by Earth, Wind & Fire.
我喜欢听 Earth, Wind & Fire 的《九月》。
九月结束时叫醒我
Every September, I think of the song 'Wake Me Up When September Ends'.
每年九月，我都会想起歌曲《九月结束时叫醒我》。
Use September naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
Sept意为七，九月却是第九个月，记作七加二等于九。
九月是中性词，适用于任何正式或非正式场合，常见于日期表达、计划安排等。
Words ending with -ber: November, December, member, and remember all rhyme with September (stressed /ɛm/ + /bər/). October has a different stressed vowel (/oʊ/), and number has /ʌ/, so they do not rhyme despite the similar spelling.
Dictionary facts from ECDICT.