Today i have learned knowledge.
1.i have been a teacher for years now.
2.i was a teacher for years
3. could you help me take a coffee
4.would you like me to take a coffee
总结 would you like me to do sth 是我能为你做些啥
could you helpe me 是希望你能帮我做些啥
i have been 意思是 action not change now 中文就是 一直 ，去过
i was a teacher 意思是 the action has changed now.