Complete the GRAMMAR FOCUS. Which past model structures in blue in Exercise 4 complete the examples? GRAMMAR FOCUS Past modal structures • You can use should/shouldn't have + past participle or ought to/ought not to have + past participle to criticise a past action or show regret. I should have listened to your advice. if it was real gold. 12 • You use had to/didn't have to + infinitive to say a past action was necessary/unnecessary. We to the doctor's. • You can also use didn't need to + infinitive or needn't have + past participle to say a past action was unnecessary. There is a difference in meaning: I didn't need to bother = I didn't bother, because it wasn't necessary. 14 = I bothered, but it wasn't necessary. E: How was | Focus 4. Second Edition. Student's Book | 5/58