If you want to know whether you are fit to learn history and geography, you’d better _________ your head teacher.

Some famous singers live on the________from their record sales.

By and by, _____ go out to contact other people in person, more and more people tend to socialize with others via electronic devices.

Recently,  many parents choose to rent a house near schools and ______their children during their school years.

—Why didn't Mr.Smith arrive on time for the meeting?—He must have been ________ on his way here in the traffic jam.