There are 30 classrooms ____________ our school. Mine is _____________ the second floor.
Jack _______ swim when he was five years old.
I think this problem is _______ that one.
Mrs Li is planning ______ Beijing with her cousin.
—I’d like ______ dress. What about ____ blue one? —Try it on.
— We really shouldn’t use plastic bags any more when shopping. — It’s important to protect our environment.