The old lady likes to keep things in the house, _____ throw them away, though many are useless.
According to the air traffic rules, you ___ switch off your mobile phone before boarding.
When I was young, I was told that I ______ play with matches
-What sort of house do you want to have? Something big? --Well, it ______ be big--that's not important.
—I can’t find my purse anywhere. —You __ have lost it while shopping.
Although this ____ sound like a simple task, great care is needed.