When we talk about a specific time of the clock or the calendar – for example 5pm or Easter – we use the preposition ‘at’, e.g. ‘I have an appointment at 5pm,’; ‘the meeting finished at 10am’, and so on. To answer the question we asked on Facebook – should we say ‘I’ll see you at Christmas’ or ‘I’ll see you on Christmas’? – the correct choice should be ‘at Christmas’, as Christmas is a specific period on the calendar.

If we mention a more general time of day – morning, afternoon or evening – we use ‘in’ followed by the definite article ‘the’, e.g. ‘She’s leaving in the morning,’; ‘the bus arrives in the afternoon’; ‘I’m meeting her in the evening’.

If we talk about yesterday, today, tomorrow, last week, next week, last month, next month, last year, next year, this morning, every – we generally do not use a preposition or the definite article. ‘See you tomorrow’ is fine – not ‘See you on/in/at tomorrow’.

Night-time is a bit more difficult. Unlike morning, afternoon or evening, if we wish to talk about an arrangement at night, we would not use ‘in the’. If, say, we are arranging to meet someone at 11pm, we would say ‘see you tonight’ or ‘see you at 11pm’, not ‘see you in the night’.

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e.g. ‘I’m meeting him tonight’ would be acceptable: ‘I’m meeting him at/in the night’ would sound very strange. ‘The bus leaves tonight’ – not ‘the bus leaves in the night’.

NB: If we are talking about a general night-time occurrence then we would use either ‘at’ or ‘in the’ (though ‘at’ is much more common in this sense), e.g. ‘Ghosts scare people at night.’

If we talk about a particular day or date, we use ‘on’, e.g. ‘My birthday is on the 31st January,’; ‘the exam is on Thursday’.

If we add a general time of day here – for example ‘Thursday morning’ – we would still use ‘on’, e.g. ‘on Monday evening’.

So if we were to talk about our plans for Christmas Day, we would use ‘on’, as it is a particular day. If we talk about a longer period – for example, Christmas, as mentioned above – we would use ‘at’.

Some more examples of longer periods of time: a month, year, decade, century or even a season (winter, spring, summer, autumn) – remember, we use ‘in’, e.g. ‘in summer it gets hot’; ‘The Beatles started out in the 1960s; ‘I start my new job in November’; ‘He was born in 1975’. This is also true when we talk about the past or the future (e.g. ‘In the future, everyone will be a robot.’; ‘in the past, people used horses to travel’.)

We also use ‘in’ to say how long it takes to do something – ‘I will pass the exam in a month’s time’.

Take our test to see how much you understand about prepositions relating to days and dates.

A. Porter

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