If you want to write clear, correct English, you certainly need to pay attention to the grammar rules. To help you with that, we collaborated with the folks from Grammarly and Write To Done to create a list with 30 common grammar mistakes you should avoid. Enjoy!
Mistake 1: Using whom as a subjectINCORRECT: Fire personnel radioed deputies to stop the driver, whom, according to reports, appeared to have been under the influence of intoxicants.
CORRECT : Fire personnel radioed deputies to stop the driver, who, according to reports, appeared to have been under the influence of intoxicants.
In this sentence, the pronoun is the subject of the verb appeared and therefore requires the subject form who. The object form of who is whom, which functions as the object of a verb or as the object of a preposition:
"That is the man whom I saw at the window. (object of the verb saw)
Did he say to whom he sent the letter? (object of the preposition to)"
The misuse of whom as a subject frequently occurs when a phrase intervenes between the pronoun and its subject. Be especially careful with such expressions as “according to so-and-so,” “in my opinion,” “one suspects,” etc. Less frequently, but more embarrassingly, whom is sometimes substituted for who when little or nothing stands between it and its verb, as in this sentence taken from a news account: “An off-duty fireman whom lives in the area provided immediate assistance.”
Mistake 2: Unnecessary would in a wish about the past
INCORRECT: Ten Things I Wish I Would Have Known When I Was Twenty
CORRECT : Ten Things I Wish I Had Known When I Was Twenty
The opportunity for knowing the ten things existed in the past, but exists no longer. The tense required, therefore, is the past perfect (had + past participle).
Mistake 3: Dangling modifierINCORRECT: At the age of four, Sam’s family moved from Florida, Missouri, to Hannibal.
CORRECT : At the age of four, Sam moved with his family from Florida, Missouri, to Hannibal.
Modifiers should be positioned as closely as possible to the element they modify. The modifying phrase “At the age of four” modifies “Sam,” not “Sam’s family.”
Mistake 4: Subject-Verb disagreement with delayed subjectINCORRECT: There goes Sally and Greg on their way to the movies.
CORRECT : There go Sally and Greg on their way to the movies.
Subjects and verbs must agree in number. When a sentence begins with here or there, the true subject of the sentence follows the verb. “Sally and Greg” is a plural subject, so the verb go must also be plural: “Sally and Greg go.”
Mistake 5: Incorrect use of object pronounsINCORRECT: Me and my brothers all have college degrees in business.
CORRECT : My brothers and I all have college degrees in business.
Several English pronouns retain different forms that indicate their function in a sentence. Me is an object form. In the example, it is incorrectly used as the subject of the verb have. Other object forms often used incorrectly are him, her, us, them, and whom.
Mistake 6: Incorrect use of subject pronounsINCORRECT: The owner was most kind to my wife and I as we toured the grounds.
CORRECT : The owner was most kind to my wife and me as we toured the grounds.
I is a subject pronoun form. It is correctly used as the subject of a verb. Its object form is me, which is used as the object of a verb or, as in this example, the object of a preposition (to). Not all English pronouns retain an object form. The pronouns that do have subject and object forms are he/him, she/her, we/us, they/them, and who/whom.
Mistake 7: Inappropriate use of reflexive pronoun formsINCORRECT: Jack and myself built the company from scratch.
CORRECT : Jack and I built the company from scratch.
A pronoun that ends in -self or -selves is called a reflexive pronoun. This type of pronoun refers to a noun or personal pronoun that occurs elsewhere in the sentence. For example, “He cut himself shaving.” In this example, himself refers to the same person as the one meant by He. A typical error is to use a reflexive pronoun in place of a personal pronoun:
INCORRECT: Thank you for everything you did for myself and my family.
CORRECT : Thank you for everything you did for me and my family.
Note: A more polite usage is to put me last in the phrase: Thank you for everything you did for my family and me.
Mistake 8: Incorrect use of did instead of had in certain “if clauses”
One use of the conjunction if is to introduce a clause that states an action that would have changed an outcome. For example, “If I hadn’t missed the train, I would be in London now.” A common error is to use did instead of had, as in this headline:
INCORRECT: [Celebrity] thinks he would be dead now if he didn’t give up alcohol and drugs
CORRECT : [Celebrity] thinks he would be dead now if he hadn’t given up alcohol and drugs
The person mentioned in the headline actually said (correctly), “I honestly don’t think I’d be alive if I hadn’t stopped drinking.” The tense required is the past perfect (had + past participle).
Mistake 9: Incorrect irregular verb forms
Most English verbs form the past and past participle by adding -ed to the base form. For example:
walk, walked, (has) walked
believe, believed, (has) believed
jump, jumped, (has) jumped
However, a few high-frequency verbs have irregular past forms, for example:
run, ran, (has) run
go, went, (has) gone
come, came, (has) come
Errors with irregular verb forms are becoming common in the media and in articles written by university graduates. Such errors are perhaps evidence that elementary school teachers no longer drill their students on the irregular verb forms. Here are typical errors:
INCORRECT: Mary loves to read, has ran for office and has an articulate way of telling it like it is.—Biographical note, KZNU.
CORRECT : Mary loves to read, has run for office and has an articulate way of telling it like it is.
INCORRECT: Deluna-Martinez is alleged to have went into one student’s account and dropped that student’s classes.—News item, KRCR
CORRECT : Deluna-Martinez is alleged to have gone into one student’s account and dropped that student’s classes.
INCORRECT: Deep Impact could have just so happened to hit one of these cometesimals, while the gas seen before impact might have came from a different region on the comet with different chemistry.—Scientific article, NASA site.
CORRECT : Deep Impact could have just so happened to hit one of these cometesimals, while the gas seen before impact might have come from a different region on the comet with different chemistry.
Note: A cometesimal is a “mini-comet.”
Mistake 10: Omitting that when it is needed after say
When there is no intervening conjunction, that may be omitted after the verb say:
"The witness said she overheard the defendant threaten to burn the man’s house down.
However, if a conjunction such as after, although, because, before, in addition to, until, or while intervenes between the verb say and its object, that is needed to avoid ambiguity:
INCORRECT: Santana said after he stopped recording, he watched for a few more minutes but never saw anyone perform CPR.
CORRECT : Santana said that after he stopped recording, he watched for a few more minutes but never saw anyone perform CPR.
https://www.dailywritingtips.com/10-grammar-mistakes-you-should-avoid/
