We believe ________ we can find out the wonder drugs to H7N9 bird flu.
---How long have you been here? ---About half an hour, Jack ______me here.
I can still remember the first day _____I spent at school _____it were yesterday.
________an advertisement says, remember that there is ________as a free lunch in the world.
Was it on that lonely island ________the family finally ___________?
---I’m terribly sorry to have put you to so much trouble. --- ________. I know you didn’t mean to.