1. Leaving too many white spaces between words Example: To the left. Correct: To the left.
2. Missing a comma Example: If the weather remains the same we'll leave early. Correct: If the weather remains the same, we'll leave early.
3. Missing a comma after an introductory phrase Example: First of all we must make sure that the power is off. Correct: First of all, we must make sure that the power is off.
4. Missing a hyphen Example: My 3 year old son Correct: My 3-year-old son
5. Incorrect subject-verb agreement Example: The cats eats. Correct: The cats eat.
6. Incorrect capitalization Example: It's cold, But we are going out. Correct: It's cold, but we are going out.
7. Mixing up possessive and plural forms Example: My sisters car is old. Correct: My sister's car is old.
8. Incorrect agreement with noun phrases Example: I would like to buy this apples. Correct: I would like to buy these apples.
9. Commonly confused words Example: After all that running, I am out of breathe. Correct: After all that running, I am out of breath.
10. Incorrect verb form after auxiliary Example: They had ate when we arrived. Correct: They had eaten when we arrived.
Source: https://www.businessinsider.com/microsoft-data-the-most-common-grammar-mistakes-2017-3, retrieved on June 18, 2021.
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