Correct answer 1: must
Correct answer 2: can't
Correct answer 3: must
Объяснение:
Modal verb 'can'
Can is an auxiliary verb, a modal auxiliary verb. We use can to:
- talk about possibility and ability
- make requests
- ask for or give permission
The main verb is always the bare infinitive (infinitive without "to").
subject
auxiliary verb
main verb
+
I
can
play
tennis.
-
He
cannot/can't
play
tennis.
?
Can
you
play
tennis.
Modal verb 'must'
We often use must to say that something is essential or necessary, for example:
Must is a modal auxiliary verb. It is followed by a main verb.
subject
auxiliary verb
main verb
I
must
go
home.
You
must
visit
us.
We
must
stop
now.
In general, must expresses personal obligation. Must expresses what the speaker thinks is necessary. Must is subjective.
In each of the above cases, the "obligation" is the opinion or idea of the person speaking. In fact, it is not a real obligation. It is not imposed from outside.
Answer 1. had to
Answer 2. had to
Объяснение:
Remember!
We use must when we talk about necessity and rules. It is used in present.
Had to is used in past. We use it when someone is obliged to. We use it when we can’t use must.
1. Must can be replaced by have to with little difference in meaning:
2. Have to is a more informal while Must is mostly used in written orders or instructions.
3. When we are mentioning someone else's obligations, we use have to.
4. For questions it is more common to use have to instead of Must (which sounds very formal).
5. The past tense of Must is Had to:
Mustn't and Don't have to
Mustn't is a negative obligation (= it is important that you do NOT do something) while don't have to is an absence of obligation.
Mustn't = it is prohibited; it is not allowed
Don't have to = no obligation; you are not required to do something, especially if you don't want to.