The children are having fun ________ on the playground.
— you out the physics problem, Kathy?— Not yet, but I’m going to.
— John, could you please the black-board now? It’s your duty today.— OK. I’ll do it right away.
— You used to the bus to school, didn’t you?— Yes, I did. However, I am used to to school now.
— What other rules do you have in your class?— Each student has to a composition once a week.
We needn’t hurry all the way to the airport — the flight has been because of the bad weather.