What’s the matter, Mary? You looked upset.— I failed again in my math exam. I’m really sorry because I don’t want to ____ my parents down.

Do you know _her mobile phone?一 No, I think it cost her around 4000 yuan.

What are you nervous _____, Mary?[ ]

They aren’t our books. Are they___________?

You will receive a reply _______ three days.[ ]