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Which one is correct ─ "on time" or "in time"? Are both correct? If so, when is one or the other used? This has been very confusing to me. I have tried to thrash out a simple rule when one or the other could be used: "in time" could be used when you are able to take a one-off action (say "x") within due time; but, when "x" is not a one-off action ─ that is to say, is a continuous-kind of action ─ you use "on time" (or, in certain cases, even "before time") to say that "x" has been done within due time. The rule could be further explained by taking example of a train. When you refer to the running of a train, you say that the train is running "on time"; but when refer to the reaching of the train a particular station, you say the train reached the station "in time". I do not know if I am correct. Can anyone tell me if I am correct?