-- I'd like to invite you to a party tomorrow evening.-- Thank you, but ______ I'll be free I'm uncertain.
—— Jack, go and clean the blackboard. ——Why ______? I’m not on duty today.
More than one kind of English ________ all over the world.
The Wilsons lived in ________ A-shaped house in the mountain during _______ World War II.
Believe it or not, those who were _______ of stealing salt would be put to death at that time.
Not until I began to work ________ how much time I had wasted.