Since means “because”, “as” or “given that”. It introduces a reason that the listener already knows or will easily accept: Since you're here, you can help me with the boxes. Since often starts the sentence, and then a comma follows the part with the reason. It sounds neutral and works both in conversation and in essays.
How would you use since?
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Since + clause, + clause; clause + since + clause (= because, when the reason is known)
- Since you've already seen this film, you choose what we watch tonight.
- Since most of our clients live abroad, we hold nearly all our meetings online.
- Public transport should be free for students, since many of them cannot afford a car.
What changed
First versionSince the last train had already left, so we took a taxi home.
RevisionSince the last train had already left, we took a taxi home.
It may seem natural to mark the result as well, with so in the second part. But since already links the reason and the result, so a second linker is unnecessary. So was removed, and the comma after the reason stayed.
The other meaning of since is “from a time in the past until now”: I've lived in Kazan since 2019. The meaning and the verb tense help you tell them apart: I've worked here since I left school is about time, while Since I work from home, I can walk the dog at lunch is about a reason. Because sounds firmer and puts the reason in focus, so the answer to Why? can only be because, not since.
Your turn
___ you're going to the supermarket anyway, could you buy some eggs for me?
Show the answer
Since — Both people know the reason: you're going to the supermarket anyway, which is why the request makes sense. A reason like this at the start of a sentence is introduced by Since. For can mean “because” only in formal or literary writing, and it never starts a sentence. It is sometimes mixed up with since because the two also pair up in time expressions (since Monday, for two days).
Write a short request to a flatmate or a colleague. Start with Since and a reason, then ask for something specific.
Since you're working from home tomorrow, could you let the plumber in at ten?
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