Mr. Green , when did you start to work a teacher in this school?[ ]

Billy: I’ve been fixing the computer for over three hours, but it still doesn’t work. Nana: Why don’t you take a rest and try ? Maybe you’ll do better then.

How old are you?—I’m fifteen. I was born _______ 1990. [ ]

The Chinese mainland has become the world’s second______ market for iPhone.

________ is fun. I like ________.