Bem Explicado
Centro de Explicações Lda.
Inglês 9º Ano – The World of Crime – Obligation and necessity
Nome: _________________________________________________ Data: ___/___/___
Obligation and necessity: Must / Mustn’t / have to / don’t have to / need/ needn’t
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Usamos must e have to para falar sobre regras e obrigações no presente.
o Have to - quando a obrigação é uma regra.
o Must – quando a obrigação parte do sujeito.
Usamos had to para falar sobre obrigações no passado
Usamos mustn´t quando algo é proibido.
Usamos don´t have e needn’t quando falamos de algo que não é
necessário fazer
Usamos didn’t have to para falar de alguma coisa que não foi necessária
fazer no passado.
1. Imagine that you are on a summer language course in Britain. Complete the
Centre for English Studies
Edinburgh
Some helpful advice about your stay.
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Everybody (have to) has to attend classes daily, but you (× have to) don’t have
to take part in the social activities if you don’t want to.
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If anybody (need) ________________ phone home for any reason, they (must)
________________ask permission to use the school phone.
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Try to keep your room tidy. Don’t forget that your landlady (have to)
________________ clean your room.
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Remind your host that she (have to) ________________provide you with a packed
lunch for the Saturdays outings.
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If you need a student card (× need) ________________ carry a passport.
 Remember that you (have to) book a time if you want to use the tennis courts.
instructions bellow.
bemexplicado.pt
2. Complete the sentences with modal verbs and the verbs in the box
Heat
worry
Clean
have
buy
go
do
take
let
Have to/ don’t have to
o Sorry I can’t stay I really __________________ now.
o It’s ok for you. You _________________ your room every Saturday night.
o Can we eat this pie could or ________________ first?
o Kate I don´t understand the homework. What ________________?
o I can’t come out just yet. I ________________ some shopping round to
my grandmother’s.
Must / need
o I’m so thirsty. I ________________ something to drink.
o He phoned to say he´s arrived safely, so you ________________
anymore.
3. Complete the teacher rules about safety in the laboratory, using must,
mustn’t, have to or don’t have to.
RULES:
You mustn’t enter the laboratory without permission.
You ________________ eat or drink in the lab.
You ________________ bring your own lab coat.
You must wear safety glasses during all experiences.
You ________________ play around in the lab.
If you have long hair, you ________________ tie it back.
You ________________ never walk away from an experiment that you have
started.
8. You ________________ bring your own calculators. We can provide them.
9. If you break anything you ________________ to tell me.
10. You ________________ to clean all your equipment after use.
11. You ________________ write the results of your experiments in the lab. You
can do that in the library if you prefer.
12. You ________________ behave safety and sensibly at all times.
13. You ________________ leave at three thirty if you haven’t finished. The
technician will be here until five o’clock.
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bemexplicado.pt