I was under the impression that every sentence has a subject–verb–object (SVO) where S and V are compulsory and O is optional.

So basically I was wondering in the sentence "I'm Tom." is the subject "I" and the verb "am" ? But what about the "Tom" ? It simply can't be an object right?

  • 5
    Do all sentences require a subject, a verb, and an object? No. They don't. Not at all. See?
    – Robusto
    Commented Sep 1, 2011 at 13:32
  • @Robusto: That's why O is optional.
    – MSalters
    Commented Sep 1, 2011 at 13:38
  • 1
    @MSalters: So are S and V. Right?
    – Robusto
    Commented Sep 1, 2011 at 13:40
  • 1
    @Robusto: No. However, S and V might be implied. E.g. "Right?" implies "Am I right?". "No" implies "No, you're not right". Language is quite efficient in that way. But O is truly optional; "He died" does not imply any object.
    – MSalters
    Commented Sep 1, 2011 at 13:45
  • 1
    "No" => Subject = "You", Verb = "are". As Tom Au notes, "to be" is a copula and doesn't have an Object here. The order is therefore SV, consistent with the presumed SVO order.
    – MSalters
    Commented Sep 1, 2011 at 14:00

4 Answers 4


Not every sentence is SVO. SVO refers to the general pattern of those primary constituents for English and a variety of other languages when discussing language typology. It's not a language requirement.

Intransitive verbs in English, for example, don't need an object. In fact, they can't take an object:

  • He died, for example, doesn't have an object.
  • *He died poison, is not grammatical.

be (the copula) is a strange verb in most languages. Some would analyse simple sentences such as I am Tom as stative passive, with Tom being the complement of I.

  • Don't forget, SVO is the typical order, but not mandatory order. Yoda speakes English OVS but everyone understands him.
    – user12549
    Commented Sep 3, 2011 at 7:54
  • But just for readers here He died a horrible death is perfectly possible! Commented Sep 20, 2014 at 17:02

Like Myqlarson said, SVO merely indicates a language typology, which basic elements order in a sentence is Subject-Verb-Object. This means that these elements are typically in this position, but in the middle you might put other elements (adjectives, adverbs); there might also exist exceptions in the same language to this rule.

In your case "I'm Tom", we need to treat it a little differently. That is because the verb "To be" is not a "predicative verb" or action verb (I'm not sure if the first is the right term), but a copular verb, also called linking verb.

The difference is that when you have a copular verb, the verb plays the role of defining the subject together with the element coming after it, such as in this case "I am Tom"; when you have an action verb, you're not defining the subject, but rather you're defining the action done by the subject (that "falls" on the object, in case there is one).

This last sentence is important because it touches your other question: not all verbs need an object, and not all verbs can stay there with only one object. This is called verb valency (I'll paste the scheme, the numbers indicate the objects taken):

  1. an avalent verb takes no arguments, e.g. It rains. (Though it is technically the subject of the verb in English, it is only a dummy subject, that is a syntactic placeholder - it has no concrete referent. No other subject can replace it.);
  2. a monovalent verb takes one argument, e.g. He1 sleeps;
  3. a divalent verb takes two, e.g. He1 kicks the ball2;
  4. a trivalent verb takes three, e.g. He1 gives her2 a flower3;
  5. a tetravalent verb takes four. Sometimes bet is considered to be a tetravalent verb in English like in the example: The fool1 bet him2 five quid3 on "The Daily Arabian"4 to win.

That kind of sentence is the main exception the SVO rule. Specifically, one where the verb is a form of "to be." Such a verb is called a "copula."

The verb "to be" connects two EQUALS. "I" is equal to "Tom" in this sentence. Therefore, "Tom" would not be an object. Instead, it would be a "subject complement."

  • not always. Note the stative passives here: The door is closed. and The cake is yummy.. They are complements, but not equals.
    – user12549
    Commented Sep 1, 2011 at 13:21
  • @myqlarson: I was talking about predicate nouns. You're talking about predicate adjectives. But you did give me an opportunity to clarify my stance.
    – Tom Au
    Commented Sep 1, 2011 at 13:40

There are all sorts of arguments about complements, which arise from Latin - lacking strict word order, Latin used the same case (nominative) for the subject and complement when the verb was the copula.

This meant that "I am Tom" ego Thomas sum and "Tom is I" Thomas ego est would not be distinguishable (well, actually, they would be because the verb-subject agreement as to person, but "Tom is a man" Thomas vir est and "A man is Tom" vir Thomas est would be).

Lots of traditional English prescriptive grammar is copied from Latin, and the rigid rule that rejects the idea of the verb "to be" taking an object and requires a complement in the nominative case (ie, "Tom is I" rather than "Tom is me") is one of those rules that makes a lot more sense in the original Latin than it does in an uninflected strict-word-order language like English.

In the example, actually, I would accept that Tom is a complement - but you should be careful; to most native speakers, subject and complement are not interchangeable; ie there is a correct word order and a wrong one.

The accusative (or objective) case for pronouns is at least as common in English as the nominative (or subjective) case when they are the complement. I would probably answer "Richard is me" to the question "Which one of you is Richard?" rather than "Richard is I". I think most native speakers would do the same, in spite of prescriptivist grammarians trying to argue for a complement in the nominative.

  • 1
    Oooh, yeah, that Latin up there hurts my head. "Thomas ego est" is all wrong. "est" is 3rd person singular: "He/she/it is". "ego Thomas sum" works, though just "Thomas sum" or "Sum Thomas" would do.
    – Phoenix
    Commented Sep 1, 2011 at 16:25
  • @Phoenix Thomas ego est is ugly as hell; you'd never say "Tom is I" in English either, but it's formally correct - Thomas is the subject of a 3rd person singular verb. And yes, I recoiled quite a bit from those, which is why I went to the Thomas vir est / vir Thomas est version as they are much nicer Latin. Commented Sep 1, 2011 at 16:29
  • FWIW, I don't think * Thomas ego est is any better than * Thomas me est, which is why Thomas sum or "I am [Richard]" are the correct usages. Commented Sep 15, 2011 at 13:20

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