15. --- Who are the teenagers gathering at the school gate? --- Well, if you _____ know, they are all my visiting students.
He used _______ on the right in China, but he soon got used ______ on the left in England.
The villagers went out to the mountain __________ the missing child.
The room _______ very useful when we had visitors.
I doubt _______ he will win or not.
-----I’m afraid I’ve broken your chair. -----.I can easily get it fixed .