What does US ?
Have you done ____ to improve the environment ?
—Who helped Betty tidy up the bedroom just now?—________. She cleaned it all by herself.
The workers in the Huashan Mountains have to ______rubbish to keep the mountains clean.
— Whose shoes are these?— They ____ be Mike’s. They are much too large for him.
The little child was too _______ to hear the end of the long speech.