-- Have you seen ______pen? I left it here this morning-- Is it ______black one? I think I saw it somewhere
Rainforests ____ and burned at such a speed that they will disappear from the earth in the near future.
—Peter, hurry up! You ______ on the phone. —Oh, I ______. Thank you.
I can’t leave the office now. A lot of work ________ to be done.
This book _____ ten units, ______ three mainly revision.
When his mother came in, the boy pretended ______.