real life pre-intermediate unit 6 obligation and permission

they have to prepare their own meals.

this sentence means:

• it's necessary to do this

• it isn't necessary to do this

• it's permitted

• it's not permitted

parents can phone and check on their children.

this sentence means:

• it's necessary to do this

• it's not necessary to do this

• it's permitted

• it's not permitted

teenagers aren't allowed to phone their parents.

this sentence means:

• it's permitted

• it's not permitted

• it's necessary to do this

• it's not necessary to do this

students don't have to work on Sundays.

this sentence means:

• it's necessary to do this

• it's not necessary to do this

• it's permitted

• it's not permitted

students are allowed to watch TV if they behave well.

this sentence means:

• it's necessary to do this.

• it's not necessary to do this

• it's permitted

• it's nor permitted

students can't have TV.

this sentence means:

• it's necessary to do this

• it's not necessary to do this

• it's permitted

• it's not permitted

we use can or is/are allowed to to talk about things that are:

• necessary

• unnecessary

• permitted

• not permitted

we use can't or is/are not allowed to to talk about things that are:

• necessary

• unnecessary

• permitted

• not permitted

we use have to to talk about things that are:

• necessary

• unnecessary

• permitted

• not permitted

we use don't have to to talk about things that are:

• necessary

• unnecessary

• permitted

• not permitted