—Are these books ____?—No, they are not his. They belong to ____.
We drove our car to go _________ the tunnel.
Nobody helped me. I finished it by _________.
My pen pal Ann found it difficult ______ Chinese well.
---Can you tell me why you learn English so well ? ---It is very simple. _______ you work, ______ grades you will get.
---How is Susan? ---Oh, she lives abroad, so I ______ ever see her.