A Common Error with 'Do/Does/Did' as Auxiliary Verbs

These sentences show a common error when using 'do/does/did'.

• She didn't liked the present I gave her. ❌
• When did the children made these decorations? ❌
• ​​Does your girlfriend works at the same company? ❌
• ​Does the school accepts transferees? ❌
• My roommate doesn't organizes her makeup on our vanity table. ❌

​You've probably spotted the error in these sentences already. 

Let's review the correct structure:

• ​do/does/did + verb in its BASE form (no -s, -ed or -ing ending)

Whenever you use do, does, or did in a question or negative sentence, the main verb must be in its base form (= the infinitive without "to"; the verb's simplest form, with no -s, -ed, or -ing ending).

Why? The auxiliary verbs do, does, and did already carry the tense, so there is no longer any need to change the main verb.

Quick Fix: 
After do/does/did, always check that the verb is in its base form:

• ❌ She  didn't liked the present I gave her. → ✅ She  didn't like the present I gave her. 
• ❌ When did the children made these decorations? → ✅ When did the children make these decorations? 
• ❌ Does your  girlfriend works at the same company? → ✅ Does your  girlfriend work at the same company? 
• ❌ Does the school accepts transferees? → ✅ Does the school accept transferees?
• ❌ My roommate doesn't organizes her makeup on our vanity table.  → ✅ My roommate doesn't organize her makeup on our vanity table. 

​
Another error to look out for:

Another common mistake is using do, does, or did with modal verbs (can, could, should, must, may, might, will, would). However, modal verbs already act as auxiliary (helping) verbs, so they do not need do/does/did for forming questions or negatives.

Key Rule:
When forming a question with a modal verb, use the modal itself as the auxiliary verb—do/does/did is not needed. For questions using modal verbs, start with the modal verb, followed by the subject and the base verb. 

• ​modal verb (can, should, etc.) + subject + verb in its BASE form

 
Examples:

• ❌ Does she can drive?  →✅ Can she drive?
• ❌ Do you will need loudspeakers?  →✅ Will you need loudspeakers? 
• ❌ Do they should change the background colors?  →✅ Should they change the background colors?
• ❌Does the government should impose stricter regulations for companies selling imported products? →✅  Should the government impose stricter regulations for companies selling imported products?

The key takeaway? If you're using do, does, or did, make sure the main verb stays in its base form. And if you're asking a question with a modal verb, skip do/does/did—the modal itself does the job!

Keep practicing, and soon this will feel completely natural!