I didn't know _____ you were getting on well with your work. 

You can only be sure of _______ you have at present; you cannot be sure of something _______ you might get in the future.

 Living on campus teaches the college freshmen ___________ to get along with all types of people and care for others.

-----What upsets him?-----_____ his computer is out of order．

Please call my secretary to arrange a meeting this afternoon, or ______ it is convenient to you.