Supply the correct tense of the verbs in brackets

7. I (buy) that hat if were not so dear.
8. You (kill) yourself if you always work as hard as that
9. If they had waited, they (find) me.10. I'm sure she will do well if she (go) to the University
11. If it (be) fine tomorrow, I shall play tennis
12. I shouldn't have thought it possible unless i (see) it
13. I'm sure my sister would go out with you if you (ask) her nicely
14. We (enjoy) the play better if it had not been so long
15. they would do it if they (can)
16. if dinner is not ready, i (go) without it
17. i (show) you how to do it if I knew myself
18. if the dog had not woken us, we (never hear) the burglar​

Supply the correct tense of the verbs in brackets