 English prepositions, in time and on time. Use on time when there is a specific time when something is supposed to or expected to happen, and it does happen at the planned time. For example, if I have a job interview at 4 p.m., if I arrive at 4 p.m., I am on time for the interview. The flight is scheduled to leave at 10.30 a.m. If it does leave at 10.30, it is leaving on time. The class is supposed to start at 9 o'clock. If it did start at 9 o'clock with no delays, it started on time. You can say he's always on time to describe a person who is punctual, who always arrives at the correct time, and is never late. But if you say he's never on time, that means he always arrives late. Use in time when something happened before it was too late, before something bad would have happened. For example, the accident victim was seriously injured. They got him to the hospital just in time. It means they got the victim to the hospital before he died. I missed the opportunity to go to that college because I didn't submit my application in time. It means I didn't submit my papers before the deadline, and the bad thing that happened was I missed the opportunity to attend that college. I left home early and arrived in plenty of time to catch my flight. That means I arrived at the airport early, with lots of time before the flight left. I got stuck in traffic and arrived just in time to catch my flight. The expression just in time means at the last possible moment, just before the flight left. We also have the expression in the nick of time to describe something happening at the very last moment before the limit, or before it's too late. The assignment was due at 4 p.m., and I emailed it to the teacher at 3.58 in the nick of time. In movies, a specialist often disarms a bomb in the nick of time, with only a few seconds left on the countdown. For more English tips, e-books, and courses, visit espressoenglish.net.