---Whose book is this? ---It ______ be Linda’s. It has her name on it.
—The food here is very nice.Thank you for inviting me.— _____ I’m glad you enjoyed it.
— Kitty, do you know ______?— Sure, about forty minutes.
The mobile phone has changed people’s life a lot ________ it was invented.
I have so much homework to do that I don’t know ________.
---- You don't know what great difficulty I had _____ to get the two tickets.---- But the film is really worth_______ twice.