①in+月、年 the morning/afternoon/evening/a week 表示时间
②on+具体某一天(几月几日)/某个假期(…Day)
③at+具体某点时间、某个假期(…Festival)/the weekend
①in…street 表示方位
②on…road/left/right
③at the…crossing/stop/某个具体的地点
①in the tree(不是树上长出来的)
②on the tree(树上原来自己长出来的)
表示时间：
① ago(……以前) later(……以后)
② before (在……以前) after(在 ……以后)
be 动词和助动词
1. be 动词(am/is/are)
主语 be 动词(原形) be 动词(过去式)
I am was He/she/it is was
We/you/they are were
2.助动词(do/does/did)
Do+非第三人称单数 +动词原形…?
…do/don't
Does+第三人称单数
…does/doesn't
Did+所有主格
…did/didn't
What do you/they/we…
+动词原形?
I/They/We+动词原形…。
What does he/she/it…
He/She/It +(动词+S)….
What did you/they/we/ he/she/it…
I/They/We/ He/She/It +动词过去式。
