Grammar Tips: Subject and Object Complements

In grammar, a complement is a word or group of words that completes something. Many phrases and clauses need a complement to make sense. As such, knowing how subject and object complements work can help you to write clearly.

Subject Complements

A subject complement follows a linking verb in a clause to describe or reidentify the subject. It can be a noun, noun phrase, pronoun, adjective, or adjectival phrase.

For instance, one common linking verb is ‘be’ (in its many and various forms). And to specify what something ‘is’ in a clause, we need to add a complement:

Here, the subject complement is ‘important’, which tells us something about the subject. We can see a complement that reidentifies the subject in the following:

In this case, the noun phrase ‘a good proofreader’ works as a single complement, telling us something about the subject ‘Janine’. Other linking verbs, like ‘appears’, ‘seems’, ‘tastes’, and ‘smells’, work similarly. For instance:

Importantly, none of these sentences would make sense without their complements. A linking verb always needs a complement to link to!

Object Complements

An object complement follows a direct object to describe or rename it. As above, this can be done with a noun, noun phrase, pronoun, adjective, or adjectival phrase. These complements are common when using verbs related to making or naming:

But there are plenty of other cases where a direct object can take a complement. It all depends on the verb and object in question. For instance:

In all cases, an object complement provides extra information that is essential to what is being said. Were we to drop ‘president’ from the last example above, for instance, we’d be left with ‘We voted him’, which is an incomplete thought.

Proofreading for Grammar

A common error is using an adverb as a complement instead of an adjective. For instance, it might be tempting to use the adverb ‘badly’ after the verb ‘tastes’:

This cake tastes badly.

This is an easy mistake to make because, usually, you modify a verb with an adverb. But using an adverb here would modify the action of tasting, not describe the thing being tasted. In other words, it would imply that the cake is bad at tasting.

If we see ‘tastes’ as a linking verb, we realise the clause needs a complement. And since we’re completing rather than modifying the verb, we use an adjective:

This cake tastes bad.

Hopefully, this has clarified the basics of subject and object complements. To make sure your writing is always clear and correct, though, why not submit it for proofreading? You can even get your first 500 words checked for free.