Prepositions of time

in  periods of time: in the evening, in my lunch break, in the summer, in the 20th century  points at the end of a period of time: in five minutes, in an hour, in three weeks, in a year on  days: on Monday, on Saturdays, on Christmas Day, on Monday afternoon, on her birthday  dates: on July 4th at  a point in time: at 3 o’clock, at midday  holiday periods: at the weekend, at New Year

in the night / at night You say in the night for something that happened on a particular night: I received a call in the night from my colleague in China. You say at night for something that happens regularly: I often have conference calls at night with my colleagues in China.

in time / on time Use in time to say something happened early enough (not too late) before a point in time: We finished in time to catch the last train home. (= I wasn’t too late to catch the last train home.) Use on time to say that something happened at (or possibly before) a previously planned time. It was punctual and not late: Always arrive on time for a meeting. (= Never arrive late for a meeting.)

in / within Use in/within to emphasise that there is a time limit: He’ll be here in three hours. (= He’ll arrive at the end of the three-hour period.) He'll be here within three hours. (= He’ll arrive at some point before the three-hour period ends.)

in the end / at the end Use in the end to talk about the final result of something or what finally happened: It lasted such a long time that in the end I feel asleep. Use at the end to talk about the time when something ended: At the end of the meeting, we talked about the time and date of the next meeting, (don’t say In the end of the meeting) The next meeting is at the end of the month, (don’t say in the end of the month)

No preposition You do not use in, on or at with: tomorrow/yesterday: I didn’t see you on yesterday. Are you coming on tomorrow? last / next / every / each + noun: We'll meet in next month. The office meeting is on every Monday.

You do not normally use the preposition with questions about time: What time is the meeting (at)? What day did you meet him (on)?