How to write compound sentences with and, but, or, so
Short answer: A compound sentence joins two complete sentences with and, but, or or so. Choose the joining word by the job it does: and adds an idea, but shows a difference, or gives a choice, and so shows a result. Put a comma before the joining word: It was cold, so we stayed inside.
🎯 I can join sentences with and, but, or, so.
At a glance
| Word | Job | Rewrite example |
|---|---|---|
| and | adds | I like tea. I like coffee. → I like tea, and I like coffee. |
| but | shows a difference | He is small. He is strong. → He is small, but he is strong. |
| or | gives a choice | We can walk. We can ride. → We can walk, or we can ride. |
| so | shows a result | It rained. We stayed in. → It rained, so we stayed in. |
How to write it
- Write two short sentences.
- Ask how they are related: added, different, a choice or a result.
- Choose and, but, or or so.
- Join the sentences with a comma and the joining word, then read the new sentence aloud.
Rewrite practice
- Before:
The shop was closed. We went home.
After: The shop was closed, so we went home.
so shows the result. - Before:
She likes cats. She does not like dogs.
After: She likes cats, but she does not like dogs.
but shows the difference. - Before:
You can sit here. You can sit there.
After: You can sit here, or you can sit there.
or gives a choice. - Before:
I bought bread. I bought milk.
After: I bought bread, and I bought milk.
and adds another idea.
Common mistakes
Because it was cold, so we stayed in.→ It was cold, so we stayed in.
Use because or so, not both.I like tea, but I like coffee.→ I like tea, and I like coffee.
There is no difference, so use and.He is tired but he works.→ He is tired, but he works.
Put a comma before but when it joins two sentences.
Compound and complex sentences
A compound sentence joins two equal ideas. A complex sentence has a main idea and an extra idea that starts with a word such as because or when.
| Type | Joining words | Example |
|---|---|---|
| compound | and, but, or, so | It rained, so we stayed in. |
| complex | because, when, if | We stayed in because it rained. |
Check yourself
- Choose: “She is shy, ___ she sings well.” (and / but)
Show the answer
but Shy and sings well are different.
- Choose: “It was late, ___ we went home.” (so / or)
Show the answer
so Going home is the result.
- Fix: “I like tea, so I like coffee.”
Show the answer
I like tea, and I like coffee. so is for results, not for adding.
Rule cards that help
- Subject + Verb: A sentence needs someone or something (the subject) and a verb: Birds fly.
- Verbs can have an object: Some verbs can have an object: the person or thing that gets the action.
- Joining words: and, but, or, so: and, but, or and so join two ideas of the same kind.
- can and can't: Can tells what someone is able to do. Can't means cannot.
- Negatives: not with be and can: To say no with am, is, are or can, add not: I am not, she isn't, they aren't, it can't.
- Negatives: don't and doesn't: To say no with an action word, use don't or doesn't and then the plain action word.
Sounds that help
- Weak & Strong Forms: and, or, but are said quickly
- Rhythm & Chunking: Pause between the two ideas
Questions
Do I always need a comma?
Put a comma before and, but, or and so when they join two full sentences. For two single words, you do not need one.
Can I start a sentence with and or but?
In speech, yes. In careful writing, join the sentences in the middle.
Where is the grammar rule?
The rule article for joining words explains and, but, or and so in detail.
Part of 🔗 Join ideas: and, but, or, so (stone 1 of the Learning Path). See also the English writing guide. Đọc bằng tiếng Việt.
Written for English learners by the English for Fun team. How we write our lessons · Last updated 2026-11-05.
Reviewed by Chinh Q. Hoang, PhD, founder, English for Fun · 2026-10-30