We have _________ some organizations to help the poor students in the western areas of China.
----Did you go to Jack’s birthday party?---No, I____.
--- Did I lock the door when I went out?--- Yes, you did. I saw you _____ it.
---You have to work very hard in your job, don’t you?----Yes, but I don’t mind that. I _____ hard.
--- I don’t know ______ my telephone number.--- Through a friend of mine.
---David,is that man your Chinese teacher?---It___________ be him.He’s having a meeting.