6. Fill the spaces in the following sentences by using one of these forms + the perfect infinitive of the verbs in brackets.
must + perfect infinitive is used for affirmative deductions can't/couldn't + infinitive is used for negative deductions. needn't + perfect infinitive is used for a past action which Was unnecessary but was performed.
11. I phoned you at nine this morning but got no answer. ~ I'm sorry. I .. (be) in the garden. 12. I left my bicycle here and now it's gone. ~ Someone ... (borrow) it. * 13. When she woke up her watch had vanished. ~ Someone ... (steal) it while she slept. 14. I've opened another bottle. ~
You ... (do) that. We've only just started this one. 15. The machine said, "You weigh 65 kilos," and I said, "Thank you." ~ You ... (say) anything. 16. I told him to turn left and he immediately turned right! ~ He ... (understand) you. 17. Perhaps he swam across. ~ No, he ... (do) that; he can't swim. 18. Do you remember reading about it in newspapers? ~ No, I ... (be) abroad at the time. 19. He ... (walk) from here to London in two hours. It isn't possible. 20. He was very sick last night. ~ The meat we had for supper ... (be) good.

11. I phoned you at nine this morning but got no answer. ~ I'm sorry. I (must have been) in the garden.

12. I left my bicycle here and now it's gone. ~ Someone (must have borrowed) it.

13. When she woke up her watch had vanished. ~ Someone (must have stolen) it while she slept.

14. I've opened another bottle. ~You ... (needn't have done) that. We've only just started this one.

15. The machine said, "You weigh 65 kilos," and I said, "Thank you." ~ You (needn't have said) anything.

16. I told him to turn left and he immediately turned right! ~ He (mustn't have understood) you.

17. Perhaps he swam across. ~ No, he (couldn't have done) that; he can't swim.

18. Do you remember reading about it in newspapers? ~ No, I (must have been) abroad at the time.

19. He (can't have walked) from here to London in two hours. It isn't possible.

20. He was very sick last night. ~ The meat we had for supper ... (mustn't have been) good.