---Do you know about a very popular toy--- the yo-yo(悠悠球)?---Yes. Filipinos(菲律宾人) invented it ________ accident. And it ________ helping kill animals.
Could you please tell me____?
-____ day it is! ---Let’s go out and enjoy the sunshine.
I’ll go to visit my aunt in England ____ the summer holidays start.
My friend is coming to visit us.I’m looking forward ____ him.
The policeman doesn’t think teenagers ____ drive.