7C - Could you pass the test?
Obligations
There are multiple ways of conveying obligations, but the most common way is Must and Have To.
Let’s start with Must!
Must is a modal verb, so, it’s followed by the base form of the infinitive (Without to.)
Another thing: You NEVER put an s at the end of the verb.
Examples:
- You must to go. INCORRECT
- You must go.
- He must waits. INCORRECT
- He must wait.
Example sentences:
- I must study.
- He must wear a helmet when he rides his bike.
- She must see a doctor before it gets worse.
- They must follow the rules.
What is must used for?
It’s used to express obligation or duty, and also refers to complying with rules, laws, and regulations.
- You must wear a seatbelt at all times.
It’s also used to emphasize the necessity of something.
- Plants must have light and water to grow.
It’s also used for deduction, when you’re sure something is true.
- Look at all of that snow. It must be really cold outside.
It’s also used to express positive logical assumptions about the past. (Must + have + past participle.)
- He must have won the lottery with the new house and car he has just bought.
It’s also used for strong recommendations or advice.
- The cupcakes here are delicious. You must try one.
The negative of Must is Mustn’t
Mustn’t is a contraction, or short way of saying Must not.
Mustn’t is a negative obligation. It is important that you do NOT do something.
In a way, mustn’t is the same as saying it is prohibited or it is not allowed.
Sometimes, HAVE TO is used instead of MUST
For example:
- I must write a letter to john.
- I have to write a letter to john.
We generally use must when the speaker decides that something is necessary, or needs to be done.
In this case I have decided that I need to write a letter to John. Nobody else has told me to write it. I think it is necessary.
We use have to when somebody else other than the speaker has made the decision.
So here, I didn’t decide to write a letter. Somebody else has told me to write it, somebody else told me it was necessary to do.
Different tenses:
The past tense of Must is Had to:
- I had to pay my speeding ticket yesterday.
- She had to give a presentation to her boss.
The future tense of Must is Will have to:
- I will have to leave work early tomorrow.
In spoken English we would use the contraction I’ll instead of I will. I’ll have to leave…
However, sometimes Must is also used to express future obligation.
- I must leave work early tomorrow
Though the version with will have to is much more common.