Modal verbs features: Modal verbs have more than one meaning: I can swim ability

Needn’t (do) or don’t/doesn’t need to (do) means it’s not necessary to do something:

You’ve got plenty of time you needn’t hurry or don’t need to hurry.

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  Needn’t have (done) is used to say that someone did something but it wasn’t necessary:
  

Ann bought some eggs but when she got home she found that she already had plenty of eggs. So she needn’t have bought any eggs.

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  Didn’t need to is used to say that an action was unnecessary. This was known at the time of the action:
  

I didn’t need to go, so I didn’t go.
I didn’t need to go but I decided to go anyway.

UNIT 14. SHOULD

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  Should expresses mild obligation and it’s used to give or to ask suggestion or advice. Should (do) means it’s a right or good thing to do. Shouldn’t (do) means it isn’t a good thing to do:
  

You should study hard.
You shouldn’t waste your time.
Should I wash my hands before a meal?

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  Should can be used with I think… structure to ask for or to give an opinion about something:
  

I think the government should do something about the economy.
I don’t think you should work so hard.
Do you think I should apply for this job?

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  Should is also used to say something is not ‘right’ or not what we expect:
  

The price on this packet is wrong. It says 65 pence but it should be 50.

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  For the past, we use should have (done) to say that someone did the wrong thing:
  

Hello, Ann. The party last night was great. You should have come. Why didn’t you?

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