The teacher began by _____ us where the city was and went on ______ about its history.
She locked her room _____ a thief would break into it.
She said she would spend her holiday ___ Beijing.
Whenever I go to Beijing, ____ is quite frequent, I will go to visit the Great Wall.
Who is it up ____ decide whether to go or not?
Wang Mei is one of many Chinese teenagers _____ “on the go”