基本规则
在英语中，表示时间时常用的介词有 in、on 和 at。它们的使用取决于时间的“粒度”：
- in：用于较长的时间段，如年份、月份、季节等（例如：in 2025, in June, in summer）。
- on：用于具体的某一天或日期（例如：on Monday, on June 5th, on Christmas Day）。
- at：用于具体时刻（例如：at 3 p.m., at noon, at midnight）。
“in June” vs “on June”
✅ 正确用法：in June
We will start the project in June.
❌ 错误用法：on June（除非后面接具体日期）
✅ Correct: The meeting is on June 15th.
❌ Incorrect: The meeting is on June.
❌ Incorrect: The meeting is on June.
总结：单独说“六月”时，用 in June；如果说“六月某日”，则用 on June + 日期。
更多示例
She was born in June.
They got married on June 20th.
I’ll see you in the morning.
The concert starts at 7 p.m.
They got married on June 20th.
I’ll see you in the morning.
The concert starts at 7 p.m.