-- Ann is in hospital. -- Oh, really? I _ _ know. I go and visit her.
— In order to improve your English, you need to practice more.— ______. Practice makes perfect.
How the fire in the dancing hall started _________ a mystery.
Please don’t try to back out _____ everything has been arranged.
Simon is very regretful. If he had been more careful, he _____ such a big mistake.
______ by jeep, we visited a number of cities in South China.