He promised to do what he ______ sure of _______.
-Oh, Mum, just a few minutes.-Hurry up, Harry. Or by the time you pack your belongings, the flight __________!
__________ I see him, he looks sad.
By the time you have finished this book, your meal __________ cold.
-Do you think that housing price will keep __________ in the years to come?-Sorry, I have no idea.
If you want to avoid the risks of passive smoking, you can ask the smoker not to __________ in front of you.