1.Our history teacher told us that the earth _________ (be) round.
2.My mother (cook) in the kitchen when you called her at 6 o’clock this afternoon.
3.They won’t go home until their homework _______ (do).
4. Please knock at the door before _________ (enter) the teachers’ office.
5. ____________ (learn) English well , he practices speaking and reading every day .