【2022.7.1】比较和详细解说 Must | Have To | Shoul
本节课分成五部分：
- Obligation - present
- Obligation - past
- Probability - present
- Probability - past
- should
- Obligation - present
rules/regulations
You must check in 40 mins before the time.
forbiden/prohibited - must
have to: necesary
You have to practice if you want to improve
I have to .....
have to (in negative)
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you must not : it's forbidden
you don't have to: you can if you want
2.past
We had to check in 40 mins before ..
3.probability
He must be working
I must have the wrong number.
It has to be the right number. (no other explanation)
It must be Andrew.
It has to be Andrew.
4.Probability - past
must have been ..
I must not have had the wrong number.
I must have been his brother.
It had to have been his brother.
5.should
what option is correct/the best/my recommendation?
should + have + pp
His parents didn't go to his birthday party.
They should have gone to his party.
