Languages are challenging to learn, especially English. There are many rules and structures to a language that could be clearer. That said, many common grammatical errors are just baffling.
As a reminder, homophones are words pronounced the same but can have different meanings and spelling. Their, they’re, and there are often mixed-up in writing—a lot.
An apostrophe marks contractions, possessives, and plurals–most frustratingly misused with plurals. There is no need to add that apostrophe when talking about Cindy’s five “cat’s.” Cindy’s five “cats” works fine.
This error changes the meaning quite drastically. “Apart” indicates a separation of things, whereas “a part” means one thing is a fraction of a larger unit.
This mistake may be due to an auditory error. “Would of” sounds a lot like “would’ve” (the contraction of “would have”). And, as you probably guessed, “would have” is the correct phrase.
Grammar enthusiasts argue about using the Oxford Comma–the final comma in a series or list of things. But make no mistake, pro-Oxford Comma fans will always spot a writer who doesn’t use it.