Must: How and When to Use in English
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Must
The auxiliary verb must can express:
• Obligation, duty, or need to do something:
• Obligation, duty, or need to do something:
I must attend this meeting. I have to, I need to attend this meeting.
He must pay his taxes before the end of the month. He is obliged to pay his taxes before the end of the month.
• certainty or a logical conclusion:
It's late, he must be at home now. It's late, so I imagine he is probably at home now.
The hardware works fine, it must be a software problem. The hardware is working perfectly, so I imagine it's probably a software problem.
In its negative form, mustn't always expresses prohibition:
You mustn't talk to strangers, kid. It's forbidden to talk to strangers, kid.
Exercise 1
Fill in the blanks below with the correct form of the verb.
Tomorrow, Dr. von Headcold must an emergency appendectomy on a very sick little girl. Afterwards she will Bruno for his monthly check up, in order to monitor the state of his Anosmia. Dr. von Headcold really her job.
Tomorrow, Dr. von Headcold must an emergency appendectomy on a very sick little girl. Afterwards she will Bruno for his monthly check up, in order to monitor the state of his Anosmia. Dr. von Headcold really her job.
Fill in the blanks below with the correct form of the verb.
Tomorrow, Dr. von Headcold must [not done] perform 1 an emergency appendectomy on a very sick little girl. Afterwards she will [not done] meet 2 Bruno for his monthly check up, in order to monitor the state of his Anosmia. Dr. von Headcold really [not done] loves 3 her job.
Tomorrow, Dr. von Headcold must [not done] perform 1 an emergency appendectomy on a very sick little girl. Afterwards she will [not done] meet 2 Bruno for his monthly check up, in order to monitor the state of his Anosmia. Dr. von Headcold really [not done] loves 3 her job.
1 perform: In the simple present tense, when a verb directly follows a modal auxiliary (would, could, should etc), we must put it in the infinitive form (without 'to').
2 meet: To create the simple future tense, we take the auxiliary 'will' and follow it with the infinitive form of the main verb, in this case 'meet'. We use the infinitive form of the verb without 'to' in these cases. Note: the future progressive tense can also be used here: Dr. von Headcold WILL BE MEETING with Bruno.
3 loves: The third person form of the verb 'to love' is loves. The simple present tense can be used to describe a general feeling or opinion, such as the fact that Dr. von Headcold loves his job.
Exercise 2
Icarus's Mother : That was a really long flight, you be exhausted.
Icarus: Actually, I slept the entire time. They showed some good movies, but I not very interested.
Icarus: Actually, I slept the entire time. They showed some good movies, but I not very interested.
Icarus's Mother : That was a really long flight, you must 1 be exhausted.
Icarus: Actually, I slept the entire time. They showed some good movies, but I was 2 not very interested.
Icarus: Actually, I slept the entire time. They showed some good movies, but I was 2 not very interested.
1 must: We use 'must' here to express a likely or probable assumption or conclusion. It was a 'long flight' so Icarus 'must' be tired.
1 have: We cannot use 'have' here without the infinitive 'to' preceding it. 'You have to be exhausted' would be correct, although it is a little awkward.
1 was: 'Was be' is not a valid grammatical construction.
2 was: We need to use a conjugated verb which agrees with the past tense form of 'interested'. 'Was' is the best choice here.
2 must: 'Must' is only an auxiliary, and we need a verb here. We could not say 'I must not very interested'.
2 have: 'Have' would only work as an auxiliary in this case, and we need a verb here.
Exercise 3
Icarus: I get to work before I'm late.
Icarus's Mother : be so nervous. You'll have one of your attacks.
Icarus's Mother : be so nervous. You'll have one of your attacks.
Icarus: I must 1 get to work before I'm late.
Icarus's Mother : Don't 2 be so nervous. You'll have one of your attacks.
Icarus's Mother : Don't 2 be so nervous. You'll have one of your attacks.
1 must: We use 'must' here to express an obligation. Icarus 'has to' get to work.
1 have: We cannot use 'have' here without 'to'. 'You have to get to work' would correctly express the sense of obligation in this sentence.
1 do: 'Do' is grammatically incorrect here. We need an auxiliary to correctly complete this sentence
2 Don't: In this case we need a conjugated verb. 'Don't' correctly introduces the imperative statement.
2 Mustn't: We cannot use 'mustn't' here because we need a verb, not an auxiliary.
2 Haven't: We cannot use 'haven't' to give direct commands such as the imperative 'don't be so nervous'.
Exercise 4
Each of the following phrases could be expressed differently. Choose the appropriate corresponding sentence for each of the following phrases:
For example: You could be a better lover = I wish you were a better lover
It seems you're quite intelligent =
It's a requirement that you're intelligent =
It would be better for you if you were intelligent =
For example: You could be a better lover = I wish you were a better lover
It seems you're quite intelligent =
It's a requirement that you're intelligent =
It would be better for you if you were intelligent =
Each of the following phrases could be expressed differently. Choose the appropriate corresponding sentence for each of the following phrases:
For example: You could be a better lover = I wish you were a better lover
It seems you're quite intelligent = You must be intelligent 1
It's a requirement that you're intelligent = You need to be intelligent 2
It would be better for you if you were intelligent = You should be intelligent 3
For example: You could be a better lover = I wish you were a better lover
It seems you're quite intelligent = You must be intelligent 1
It's a requirement that you're intelligent = You need to be intelligent 2
It would be better for you if you were intelligent = You should be intelligent 3
1 You must be intelligent: This is the best choice here. 'You must be intelligent' is not a direct order for someone to be intelligent, but usually an exclamation. For example: 'I can't believe you just recited the first fifty pages of the Bible from memory! You must be intelligent'.
1 You should be intelligent: This is not the meaning of the sentence.
1 You need to be intelligent: This is not the meaning of the sentence.
2 You need to be intelligent: This is the best choice here. 'You need to be intelligent' expresses an order or requirement for someone to be intelligent, because it is 'necessary'. For example: 'This is one of the best schools in the country. You need to be intelligent if you want to get accepted'.
2 You should be intelligent: This is not the meaning of the sentence.
3 You should be intelligent: This is the best choice here. 'You should be intelligent' is synonymous with 'you ought to be intelligent' and expresses the conditional. For example: 'You should be intelligent, if you want to become an astronomer'.
3 You must be intelligent: This is not the meaning of the sentence.
3 You need to be intelligent: This is not the meaning of the sentence.
Exercise 5
Fill in the blanks using the words listed below. Be careful! Some words may be used more than once, and some not at all.
must | need to | have
Bob: Hello, I speak with Sophie Carter, please.
Receptionist: You sound worried. It be important.
Bob: It's very important. Please put her on the phone!
Receptionist: Who?
Bob: You be kidding! Sophie Carter!
Receptionist: Sorry, I don't know her. You have the wrong number.
must | need to | have
Bob: Hello, I speak with Sophie Carter, please.
Receptionist: You sound worried. It be important.
Bob: It's very important. Please put her on the phone!
Receptionist: Who?
Bob: You be kidding! Sophie Carter!
Receptionist: Sorry, I don't know her. You have the wrong number.
Fill in the blanks using the words listed below. Be careful! Some words may be used more than once, and some not at all.
must | need to | have
Bob: Hello, I need to 1 speak with Sophie Carter, please.
Receptionist: You sound worried. It must 2 be important.
Bob: It's very important. Please put her on the phone!
Receptionist: Who?
Bob: You must 3 be kidding! Sophie Carter!
Receptionist: Sorry, I don't know her. You must 4 have the wrong number.
must | need to | have
Bob: Hello, I need to 1 speak with Sophie Carter, please.
Receptionist: You sound worried. It must 2 be important.
Bob: It's very important. Please put her on the phone!
Receptionist: Who?
Bob: You must 3 be kidding! Sophie Carter!
Receptionist: Sorry, I don't know her. You must 4 have the wrong number.
1 need to: This is the best choice here. Bob is emphasizing the fact that he wishes to speak with his wife, by referring to it as a necessity.
2 must: This is the best choice here. 'Must' is often used with the impersonal subject 'it' to express a sense of urgency or certainty. 'It must be important' is one of the more common uses of 'must' in spoken English.
3 must: This is the best choice here. 'You must be kidding' is a rather common expression in informal English, used as an exclamation of surprise, which means: 'Are you joking with me?'.
4 must: This is the best choice here. 'You must have the wrong number' is a common instance of when 'must' is used in spoken English. The receptionist is telling Bob that he has obviously dialed the wrong telephone number.
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