.After boarding the plane, I found my seat _____ by a police officer, wondering whether I got the wrong flight.
----Would you please lend me the dictionary? ---- ____.
Who is it up ____ decide whether to go or not?
Wang Mei is one of many Chinese teenagers _____ “on the go”
The two boys fought and fought until one ______.
He will _____ our class to sing at the school singing contest.