* Someone left their phone on the table.
* I saw someone walking their dog in the park.
* Please ask someone to help me with this heavy box.
* Someone needs to fix this leaky faucet.
* Someone stole my wallet!
"Someone" is a pronoun used to refer to an unspecified person. It can be used in a variety of contexts, and its meaning can change depending on the context. Let me know if you'd like more examples or have any other questions about using "someone" in a sentence!