How to use the preposition by in english grammar
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We use the preposition by to talk about a means or method used to do something:
- I did it by mistake.
- Contact me by email.
- I want to pay by cheque.
⚠️ It is said to be pay cash or pay in cash (and not by cash)
We also use by to tell by which means of transport someone travels:
- He always goes to work by bus.
- She likes to travel by plane.
We can also use by bike, by ship, by train, by road, by air, by rail…
⚠️ We say on foot and not by foot.
By is used to make sentences on the passive:
- He was killed by an elephant.
- They were invited by Paul.
- She was bitten by a dog.
- The car was fixed by the mechanic.
- This house was built by my father.
By allows you to talk about an action with a goal (with a verb + ing):
- You can stay healthy by drinking a lot of water.
- By pressing this button, you turn off the computer.
To talk about the author of a work:
- I’m reading a book by Stephen King.
- It’s a film by James Cameron.
- That’s a nice song by Bruno Mars.
To describe a person:
- He’s an engineer by trade.
- By nature, she’s very nervous.
To express a difference, a deviation:
- She won by five points.
- The bullet missed me by inches.
To indicate the times of day:
- We travelled by night and rested by day.
By is sometimes used to indicate proximity:
- The bank is by the bakery.
- There’s a good restaurant by the lake.
- My parents live by the sea.
- She was standing by me.
By indicates a time limit:
- My son must be in bed by 10 o’clock.
- I’ll be there by nine.
- The letter must be sent by September 15.
By indicates a conformity with something:
- He must play by the rules.
- The elephant is an animal protected by law.
- By my watch it’s 9 o’clock.
- By my calculations, it’s too late.
By is used in calculation, measurement and quantity expressions:
- Divide/ multiply 10 by 2.
- My bed is 2 metres by 4.
- This fabric is sold by the meter.
- She’s selling cakes by the thousands.
- The company decided to cut prices by 50%.
To give his opinion:
- If that’s okay by you, I’d like to leave now.
- That’s fine by me.
To say ‘next to another thing’:
- The two girls were sitting side by side on a bench.
To say that we did something on our own:
- The dog opened the door by itself.
- I stayed at home by myself.
By the way:
- By the way, are you coming tonight?
We use by to express the frequency:
- The babysitter is usually paid by the hour.
- Climate change is deteriorating by the day.
To indicate a gradual process:
- He ate all the cakes one by one.
- House prices are climbing day by day.
- The instruction manual details the process step by step.