Do you know Jack’s telephone number—________.As a matter of fact, I don’t know any Jack, either.

I hear that your good friend David ____________ books about history.— Yes, but now he ____________ novels.

Mr. White is glad to see his daughter go to school by bike .

______________________—It is OK.

Now China has joined WTO（世贸组织）, so I think English is________ useful than before.