Pleasekeep me informed_______ the change of your address as soon as possible

Betty, could you answer my question— Sorry, Mr. Green. I didn’t hear you. I _______about something else.

Can you tell me ______ to jointhe army

The new survey shows that the number of students________computer games has been on the increase in recent years.

He kept yawning in class this morning. That is _____he stayed up late doing his homework last night.