If the words “do” or “does” are confusing to you, grammar rules can help. This guide will help you remember the difference between do vs. does.
When you are writing, verbs can be tricky. Some irregular verbs do not follow normal conjugation patterns, which can leave you wondering which one to use in a specific situation. While you can often trust your instincts based on how the sentence sounds, there are situations where it might sound right to your ear, but your choice breaks grammar rules.
“Do” or “does” grammar rules are some that are sometimes tricky. Both “do” and “does” are forms of the verb “to do,” but they have different uses based on the sentence you are writing. Understanding these will help you write clearly and accurately.
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Do vs. Does: A Comparison
The verb “to do” means “to bring to pass” or “perform, execute,” according to the Merriam-Webster Dictionary. There are several other nuanced meanings for this handy verb, but these are the more common uses in the English language.
Similarities Between Do and Does
Do and does seem very similar, and for a good reason. “Does” is simply a different conjugation of the main verb “do.”
Both “do” and “does” are present tense verbs. They can also replace another verb in a statement where the meaning is obvious. For example:
- My teacher does the math so fast!
In this sentence, “do math” refers to figuring sums or other types of math problems, and this phrase could be replaced by the verb “figure,” “calculate,” or “add/subtract/divide/multiply,” depending on the context.
Differences Between Do and Does
Even though “do” and “does” are similar, they do have some differences.
First, the word “do” has many definitions. However, “does” only applies to performing or bringing something to pass, not the other definitions of the word “do.”
Second, “do” is used for plural subjects and first-person subjects, while “does” is used for singular, third-person subjects.
Common Uses of “Do”
The word “do” has many potential uses in a sentence. It can fall anywhere in the sentence, but it is rarely the first word in a sentence that is not a question. These are the common times you will choose “do.”
Simple Present Tense with Plural Subjects
Do is the simple present tense form of the verb used with plural nouns or pronouns as the subjects and the single, first-person pronoun “I.” For example:
- I do my best in school.
- Children do well when they have the right information.
“Do” can also be a helping verb or an auxiliary verb. This form specifically shows up in questions, with negative statements or for emphasis. For example:
- Do the worksheets seem too challenging?
- I do not have many subscribers to my channel.
- The grandchildren do like pickles!
In each of these, the subject is plural, or the pronouns “I” or “you,” so “do” is the correct form.
As a helping verb, another rule applies to “do.” If a sentence uses “do” as a helping verb, you will not ever pair it with any verb form of “to be.”
Imperative sentences give the reader a command. In these sentences, you always use “do” and never “does.” For example:
Do your chores before you go outside to play.
It would be incorrect to say:
- Does your chores before you go outside to play.
This error is rare because it sounds wrong to most readers and listeners, but it is still a rule you should know.
Common Uses of “Does”
The word “does” is also the simple present tense form of the verb but has slightly fewer uses. These are:
Simple Present Tense with Singular Subjects
If you have a singular noun or pronoun, such as he/she/it, and you are speaking in the present tense, you will use “does” as the verb.
- The computer does the work for us.
- He does it well.
“Does” also plays the role of the helping or auxiliary verb in sentences with singular pronouns or nouns as the subject. This is common when writing a negative sentence, a positive sentence with emphasis, or a question, as in:
- Does he like Christmas carols?
- He does not like them.
- He does like Christmas candy, however.
Remember, in this structure, you never add an “s” to the main verb, even though the singular present tense conjugation usually requires an “s.” For instance, this is incorrect:
He does likes Christmas candy, however.
When you speak English, you likely apply this rule naturally, making it easy to apply to your written English.
Do and Does in Questions
If a question is a yes/no question, then “do” or “does” are often the verbs that start the sentence. These questions follow this format:
- Do roosters crow every morning?
This structure elicits a “yes” or “no” answer response.
For interrogative questions that require more of a response, the words “who,” “what,” “where,” “when,” “why,” or “how” will come first, followed by “do” or “does.” For example:
- Why do roosters crow every morning?
This question requires a short answer that is more than just “yes” or “no.”
Negative Forms of “Do” and “Does”
Both “do” and “does” have common contractions for their negative forms. The negative form of “do” is “do not.” Many writers or speakers will shorten that to the contraction “don’t.”
Similarly, the negative form of “does” is “does not.” Its contraction is “doesn’t.”
Here are some examples:
- They don’t want to take a vacation this year.
- He doesn’t think his doctor understands his symptoms.
Past Tense Form of “Do”
If you need to use “do” in the past tense, the correct form of the word is “did.” This conjugation applies to both singular and plural subjects. For example:
- They did well on the last examination.
- He did his job and went home.
A Final Word on Do or Does Grammar Rules
“Do” and “Does” are fairly simple verbs to keep straight. These verbs are the present-tense version of the verb “to do.” They have several uses in the English language, but you can choose properly by looking at the subject most of the time.
If the subject is singular, you will likely use the word “does.” If the subject is plural, or it is the personal pronoun “I’“ or the second-person pronoun “you,” you will use “do.”
One exception to this rule is in imperative sentences. That is one instance where you will always use “do,” even if the subject is singular.
You might also be interested in our was vs. were explainer.
FAQs About Do or Does Grammar Rules
Can you start a sentence with “do” or “does?”
Yes, the words “do” or “does” is the first word in a yes/no question. “Do” can also be the first word in an imperative sentence that gives a command. In other instances, these words do not start the sentence.
Is “Do” a helping verb?
Sometimes “do” is used as a helping verb. It can pair with the main verb in a question, as an emphasis, or in a negative sentence. It never pairs with any form of “to be.”
When editing for grammar, we also recommend taking the time to improve the readability score of a piece of writing before publishing or submitting
If you still need help, our guide to grammar and syntax explains more.
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