Subject-Verb Agreement
* Incorrect: The dog barks loud.
* Correct: The dog barks loudly.
* Incorrect: They is going to the store.
* Correct: They are going to the store.
Pronoun Agreement
* Incorrect: The cat licked its paw.
* Correct: The cat licked her paw.
* Incorrect: Everyone brought their own lunch.
* Correct: Everyone brought their own lunch. (While technically "their" is plural, it's often used in this case for inclusivity).
* More Correct: Everyone brought his or her own lunch.
Tense Errors
* Incorrect: I will go to the store yesterday.
* Correct: I went to the store yesterday.
* Incorrect: I am going to the store tomorrow, but I go yesterday.
* Correct: I am going to the store tomorrow, but I went yesterday.
Misplaced Modifiers
* Incorrect: I saw a dog walking down the street with a red collar.
* Correct: I saw a dog with a red collar walking down the street.
Incorrect: I ate the cookies on the table that were chocolate chip.
* Correct: I ate the chocolate chip cookies on the table.
Run-on Sentences
* Incorrect: I went to the store I bought some milk I went home.
* Correct: I went to the store, bought some milk, and went home.
Sentence Fragments
* Incorrect: Running down the street.
* Correct: The dog was running down the street.
Incorrect: Because I was tired.
* Correct: I went to bed early because I was tired.
Informal Language
* Incorrect: I ain't got no money.
* Correct: I don't have any money.
Incorrect: Me and my friend went to the park.
* Correct: My friend and I went to the park.
Word Order
* Incorrect: The went to store she.
* Correct: She went to the store.
Incorrect: The boy gave the apple to the girl red.
* Correct: The boy gave the red apple to the girl.
Note: These are just a few examples, and there are many other ways a sentence can be ungrammatical. The rules of grammar can be complex, but understanding the basic principles can help you write clearly and effectively.