介绍:
1. 什么是介词？
表示名词、代词与句子中其他词的关系
不能单独作句子成分（不作谓语）
后常有名词、代词（人称宾格）
2. 表示时间的介词（一）
at, on, in
at •
in ——
例子：let's meet up at 6:00pm.
I'll see you on Monday.
I met Jack in 2003.
特别补充：
in the morning/afternoon/evening
at noon/night/midnight
on Sunday morning
表示时间的介词（二）
for during from…to
例子：
It's always sunny during the summer here.
I stayed in Beijing for 2 weeks.
The movie will be on from 8:00-10:00.
3. 表示地点的介词
at in
4.表示方位的介词：
on /under/ in front of/behind/between/across from
5.表示原因的介词 because
大家还在听
