.— Liu Tao has never read the book The Adventure of Tom Sawyer, _________ he?— _________. He told me it's very interesting. He'd like to read it again.
Some of my friends are interested in science, but none of them can tell ________.
______ your English teacher ______ you ?
They were talking about the persons and things _______ they saw in the factory.
Not only the students but also their teacher_______ the Great Wall before.
It is impossible for ______ little children to do ______ much work within 20 minutes.