Prepositions govern and typically precede a noun or pronoun, expressing its relation to another word or element within the clause.
Prepositions of place
As a rule, ‘at’ is used to tell us the specific point or location of the thing to which the noun refers:
- He’s waiting at the bus stop.
- Simon is at his desk.
- I work at a pet shop.
‘In’ is used quite differently. What it does is tell us that the thing that the noun refers to is in an enclosed space, often surrounded or closed off on all sides. For example:
- Simon was sitting in a green room.
- Mary was riding in the forest.
- The cat was in a box.
‘On’ is used to tell us that the noun is located on a surface, either attached to something or touching it:
- Hector stood on the table.
- Mavis was seated on the floor.
- Albert sat on the chair.
Sometimes, these prepositions can be used interchangeably, depending on the desired emphasis. For example, we might say either:
- She’s at the shop.
- She’s in the shop.
Both are grammatically correct, but the former focuses on location, whilst the latter explains the type of building that the ‘she’ in the example is in.
It’s important to note the use of ‘at’ and ‘on’ when we’re referring to addresses. We do not use ‘at’ for addresses without house or building numbers, so rather than saying…
X She lives at Street Lane.
…We would say…
V She lives on Street Lane.
Prepositions of time
Let’s start with ‘at’. We use ‘at’ for a precise time, so we might say:
- I woke up at 11.30am.
- I had lunch with my grandmother at the weekend.
- I only said goodbye to my friends at midnight.
We would use ‘in’, on the other hand, to refer to periods of time, such as months, seasons, or years:
- I visited Greece in July.
- I haven’t smoked in three years.
- Samantha travelled to Russia in winter.
Now let’s look at ‘on’. ‘On’ is used to refer to days and dates:
- A lot of shops don’t open on Sundays.
- I took my dog to the vet on Friday.
- I spent time with my family on Christmas Day.
We do not use ‘at’, ‘in’, or ‘on’ before the words ‘all’, ‘any’, ‘each’, ‘every’, ‘last’, ‘next’, ‘one’, ‘some’, ‘this’, or ‘that’, even where these are followed by a time expression
He went on Sundays He was there each Sunday.
He was there at the weekend He was there last weekend.
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