You can come here to ask me ________ if you have any questions.
--What great changes! It’s years since we_____ each other last time . -- Believe it or not, It’s the second time that we _____a face –to- face talk
______the Internet is of great help, I don’t think it’s a good idea to spend too much time on it.
_________ you may have, you should gather your courage to face the challenge.
He made another wonderful discovery, _______ of great importance to science.
These kinds of shoes ________ well.