.—When will you be back, Peter? —___________ a couple of days.
23. Don’t try to cheat the taxman(税务人员); you’ll never ______it.
22. —Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
21. He apologized ________ late.
20. I got up early this morning, but I ________ so because I was not on duty today.
19. It’s dangerous to have the fire _______ at home all night long.