If you let challenges and difficulties benefit ______ depress you, much more can be accomplished than you thought possible.

_____ you didn’t know the rules won’t be an excuse for your failure to report.

You should be careful when _______.—Yes, I will. I’d like to know when________ to have a rest.

_________ from your family and friends, though it may cause short-term discomfort, doesn’t have to be as painful as it seems.

The number of the students in our school_________ 600, but a number of students _________ living in the school.