I think computers are very useful.They can help us get much on the Internet.
I think basketball is interesting, ______ he thinks it is ______.
— Let’s play _____ football. —That _____ good.
A set of keys ____ in the library. Are they yours?
— Where _______your books? — _______ in the bookcase
— Does David have a ping-pong ball? —________. But he has some tennis balls.