Present and past Modal Structures

I fed the cat after I got back from school in the evening. I didn’t know that my sister had fed it thirty minutes earlier.

• I didn’t need to feed the cat.

• I needn’t have fed the cat.

When I got back from school, I saw a note on the table from my sister, saying that she had fed the cat thirty minutes earlier.

• I didn’t need to feed the cat.
• I needn’t have fed the cat.

I didn’t listen to her advice, and that was a mistake.

• I should have listened to her advice.
• I ought to listen to her advice.

They didn’t live far away, so it wasn’t necessary for us to take a taxi.

• We didn’t have to take a taxi.
• We needn’t have taken a taxi.

I think it would be best if you went to the party.

• You had better not go there.
• You had better go there.

You didn’t ask for the exact address and now we don’t know where to go.

• You ought to have asked for the address.
• You ought not to have asked for the address.

Never make this mistake again – it’s very important.

• You ought to make this mistake again.
• You mustn’t make this mistake again.

It wasn’t a good idea to give him my contact details.

• I should have given them to him.

• I shouldn’t have given them to him.

It’s a shame she didn’t stay at home. SHOULD She ……………

I don’t think it’s a good idea for you to be late tonight. OUGHT You ……………