I'm teaching conversational English to ESL students in Korea, but I don't have a strong background in grammar. I can tell them how we say things, but cannot always explain why it is that way. Today, one student asked about the phrase:

"What does he do?"

They wanted to know why we use "do" at the end, and why we cannot say "What does he does?". I really wanted to answer their question, so I told them I'd answer tomorrow. Please let me know! Thank you!

  • 2
    We use the unmarked infinitive do because there's already an inflected does serving as an "auxiliary" in the construction - and only one verb can be inflected for tense/person in such contexts. Note that although it's no longer idiomatic, it's still syntactically valid to say What does he? (where it's not an auxiliary; cf "Shakespearean" What thinkst thou?). – FumbleFingers Mar 6 at 16:09
  • @FumbleFingers Would another, perhaps less technical, way of explaining that for someone like me, be to say that, the "do" in that sentence is not the indicative verb? - The latter is "does", in "does he?". The "do" is an infinitive. Only instead of asking "What does he (to) do?", by idiomatic convention we omit the "to", in an infinitive following the indicative of modals such as "do", "can", "may" etc. However the verb "to be" requires a "to" with a following infinitive - "What is he to do?", "Where am I to go?" – WS2 Mar 6 at 16:57
  • @WS2: I don't think "indicative verb" is the right term there. Perhaps the primary verb? As opposed to the "auxiliary"? – FumbleFingers Mar 6 at 17:48
  • @FumbleFingers Forgive me, but then it was drummed into me at my 1950s' Grammar School, that I would understand English better by paying attention to my Latin. Every verb was deemed to have a "mood", a "voice" and a "tense". Ah! Now you are right - it is the "interrogative" mood that is in play here, isn't it. But the "do" word is infinitive, n'est-ce pas? – WS2 Mar 6 at 19:02
  • @WS2: The "do" word certainly isn't infinitive in What do you think? (a "tensed" form, as with What does he think?). The second instance in What do you do? is infinitive, and that's precisely because when the entire construction involves an auxiliary (the first instance of do there), only one of the two (specifically, the auxiliary) can be inflected for tense/person). Note that I'm sure much if not all of what I'm saying in this comment is obvious to you anyway - I'm mainly spelling it out like this because it might help a few learners (incl. perhaps OP himself). – FumbleFingers Mar 7 at 14:16

The first and second uses of the verb do are different.

The first do ("what does") is an auxiliary verb, which doesn't have meaning on its own, except to properly phrase a question. The auxiliary do is conjugated in the typical way:

What do I...
What do you...
What does he...
What did I...

The verb that follows the auxiliary do should be in the form of a bare infinitive, that is, the infinitive minus the to. The bare infinitive form of to do is do.

So it's:

What does [auxiliary verb, conjugated in the present tense with the subject "he"] he do [bare infinitive of to do]?

As TaliesinMerlin points out, it may be helpful to think about this construction as a verb phrase. That term has multiple definitions, but here, we can think of a verb phrase just as multiple words which are used in combination as a verb. Some similar verb phrases with an auxiliary verb and a main verb are he can do and he should do.

When we use a verb phrase, only one component of the phrase is conjugated to match the subject:

I can go
You can go
He can go*

In this case, you can think of the verb phrase as he does do (an emphatic form of the statement he does), which is then inverted to form the interrogative form: he does do -> what does he do?

Other examples will follow the same pattern:

What does [auxiliary] she like [bare infinitive]?
Where did [auxiliary in the past tense] they go [bare infinitive]?
He does [auxiliary, here used for emphasis, not to form a question] think [bare infinitive]!

* This isn't the best example because can is irregular and is conjugated identically. If someone wants to edit this answer with a better example, they are welcome to do so.

  • 1
    Good work! It may also help to directly compare an interrogative and noninterrogative form, which you hint at in your last example: "What does he do?" -> "He does do that." I use that to highlight the fact that "do" is part of a verb phrase, and it's not really "he do" but "does he do" (inversion for a question) or "he does do." – TaliesinMerlin Mar 6 at 16:17
  • +1 for an ingenious answer. But the fact of the "second do" being an infinitive is clear if you make the verb "to be" the auxiliary - "What is he to do?", "What am I to think?" etc. Interestingly with do, can and should the infinitive becomes "bare". – WS2 Mar 7 at 15:57

When we ask questions about a third person, we use "What does he/why does she/where does it.....?"

We frame questions the following way in English:

What/why/where + auxiliary verb (do/does) + subject + main verb

I can ask "What does she eat?" to understand what someone eats. I might be curious because she looks great. In this question, "what" is the question word, "does" is the auxiliary verb, "she" is the subject and "eat" is the main verb. You might argue why it is "eat" and not "eats" since we're referring to a third person. That makes sense because we add "s" to a verb when we use it with a third person subject. But, you have to remember that in negatives and questions, we don't add "s" to a verb even with a third person. We just add "does not" or "does he eat?" with negatives and questions respectively. Note that the same question becomes "What do you eat?" for second person. Everything remains the same except the auxiliary verb being "do" here.

Traditionally, the verb "do" is used to ask someone about their job. In other words, what do they do for a living.

Thus, simply, we are using the word "do" as the main verb to refer to their job.

Hope I answered your question.

I recommend the following sites for great grammar info:



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