you erase the blackboard today, __________—But I did it yesterday.

The old man sat in front of the television every evening, happy ___ anything that happened to be on.[ ]

It is important ______ students ______ carefully in class .

Paper produced every year is____the world’s production of vehicles.

Dr.Peter Spence，________ headmaster of the school，told us，“________fifth of pupils here go on to study at Oxford and Cambridge.”