| in | |
| main parts of the day | in the morning/afternoon/evening: 'In the morning we went for a walk along the Seine.' Compare: at night: 'I don't like driving at night.' |
| months, years, seasons, centuries | She'll be coming back home in March.' 'In 1989 he decided to join the army.' 'They're getting married in the autumn.' 'In the twentieth century there have been two World Wars.' |
| at the end of a stated period | 'I'll be back in a couple of minutes.' 'In two weeks' time she's going on leave.' |
| on | |
| specific days/dates/mornings/afternoons, etc. | 'on Tuesday', 'on 3rd April', 'on Monday night', 'on New Year's Day', 'on the day of my arrival' |
| at | |
| clock times | 'The shops open at 9 o'clock.' 'Her flight is due in at 6.35.' |
| main points of time in the day | at midnight/noon/dawn/lunehtime, etc.: 'We usually open our presents at midnight.' 'He turned up in my office at noon, expecting a free lunch.' |
| weekend (British English) | at the weekend: 'What are you doing at the weekend?'
at weekends: 'I never do any work at weekends.'
BUT (American English) on the weekend |
| the holiday period around Christmas, Easter, Hannukkah, Ramadan, etc. | at Christmas, at Easter, at Hannukkah, at Ramadan: 'We like to stay at home at Christmas.' 'At Ramadan the roads tend to be very quiet.'
BUT on Christmas Day, on Easter Sunday |
| phrases with time | 'I'm afraid that at the present time we're out of stock.' 'You've come at a bad time.'
BUT note the idioms: in time, on time, about time |
| Note: | |
| In, on, at, etc. are NOT used before time phrases beginning with this, every and last/next (= the one that has just gone/is about to come) | We can't afford a holiday this year.' 'Where did you go last weekend?' 'My exams finish next Tuesday afternoon.'
Note also that the is NOT used in these phrases.
Compare: 'The meeting is to be held on the last Friday in April.' In this sentence last does not mean 'the one that has just gone'. |
| In, on, at, etc. are NOT used before phrases ending with ago | 'He left the office five minutes ago.' 'I first met her in Glasgow about two years ago.' |