during 与over 有什么区别？

表示时间时：during表示“在...期间”强调的是时间的长度
over 表示“多，超过”强调的是程度

时间介系词over表示超过...时间，有more than的意思。
It must be over three hours since I started working.
从我开始干到现在一定有三个多小时了。

during用来表示一段时间，其意义大致相当于in的用法。一般来说，凡是能用in的地方，也可以用during.例如：He came to see me during my absence.Don’t go to see his wife in his absence.

during强调时间的延续性
They visited many cities during their stay in China