modal verbs

Question 1

obligation/necessity

Answer 1

must
have to
should

Question 2

it is not necessary in the present or future

Answer 2

don’t have to
don’t need to

Question 3

we know that it happened in the past although it wasn’t necessary

Answer 3

needn’t + bare perfect infinitive

Question 4

it was not necessary in the past but we don’t know if it happened

Answer 4

didn’t need to
didn’t have to

Question 5

prohibition

Answer 5

mustn’t
can’t

Question 6

advice

Answer 6

should/ought to

Question 7

possibility

Answer 7

can
could

Question 8

ability and inability

Answer 8

can
could
was able to

Question 9

offers

Answer 9

can
would
shall
could

Question 10

probability

Answer 10

will
should/ought to

Question 11

premission

Answer 11

can
may

Question 12

logical assumption

Answer 12

must
may/might
can’t