Which one is correct:

"A popular approach is the so-called immersed interface methods."

"A popular approach are the so-called immersed interface methods."

In Portuguese, the second one would be correct, because the verb "to be" sometimes agrees with the object instead of the subject. I was wondering if in English such exception also exists, of if the verb "to be" always agrees with the subject no matter what.


4 Answers 4


It depends on the meaning of "immersed interface methods." If it is to be considered a a whole, a single thing, then singular is correct, if it represents many different methods consider individually, then the subject should be plural.

Let me give you an example that might help clarify. I live in the USA. I might say:

a popular country is the United States.

"States" is technically plural, so this doesn't seem to fit, but "United States" is considered idiomatically a single entity.

To give another example:

On the football squad, a popular topic of conversation is girls.

Again "girls" is plural, but it is considered just one thing for the subject of this sentence.

So for you, you have two options:

A popular approach is the so-called "immersed interface methods."

To emphasize the unified nature of the methods, I have quoted it, which helps a lot in understanding. The qualifier "so-called" adds to this a lot, indicating that it is called that as a common idiomatic construction. Or alternatively:

Popular approaches are the the so-called immersed interface methods.
  • In Portuguese, the correct agreement would be "a popular country are the United States" or "a popular topic are girls". That is why I was in doubt. Thank you for your explanation.
    – user34814
    May 1, 2014 at 0:11
  • An answer to OP's specific question needs to contain 'English does not have any exception to the rule that the verb should agree with the subject' or words to that effect. Jul 15, 2017 at 6:53

A modification of the first option:

A popular approach is the so-called immersed interface method.

English does not have any exception to the rule that to be should agree with the subject. Furthermore, idiomatic English would use the singular method rather than methods in this sentence, so the problem doesn't even apply.

  • 1
    This is the correct answer. Why the downvote? Apr 30, 2014 at 16:43
  • Thank you for your answer. But I am referring to methods, plural, because there are several methods that are described as immersed interface.
    – user34814
    May 1, 2014 at 0:13
  • Great!......I would make the subject plural also..... "Some popular approaches are the immersed interface methods." May 1, 2014 at 0:18
  • Sorry Gary but both you and Edwin (commenting on my answer above) are mistaken. It is "interface methods" that are popular, you can't just change the semantics to suit your grammar requirements. And, it is not the individual methods that are popular, but all the methods as a group that are popular. One would not, for example, say "A popular moral code are the ten commandments" you would say "is the ten commandments" since they are not considered individually but as a group.
    – Fraser Orr
    Jul 16, 2017 at 22:40

You can't say 'A popular approach' (singular), and then use 'methods' (plural). So both are incorrect.

You can have either:

A popular approach is the so-called immersed interface method.

Popular approaches are the so-called immersed interface methods.

Singular and plural respectively, if there are more than one 'so-called immersed interface methods', then use the latter.

  • 1
    How about: "A popular approach is to employ the so-called immersed interface methods." Would that be correct?
    – user34814
    Apr 30, 2014 at 16:54
  • Yes, that's ok, because 'approach' agrees with 'is'. The second half of the sentence doesn't need to agree in this case. I'm not an expert linguist so I can't explain why I'm afraid, just experience of English Language.
    – mjsqu
    Apr 30, 2014 at 17:02
  • It may be that 'the so-called immersed interface methods' is a new clause, but I'm opening myself up to any better answers from the forum...
    – mjsqu
    Apr 30, 2014 at 17:03
  • Incorrect general analysis. 'My favourite breakfast is beans on toast' is totally acceptable. Jul 15, 2017 at 6:40

It is awkward to define a single thing as being multiple things regardless of language. There is a logical gap here.

Consider that you are describing a single approach but the approach admits multiple facets. Then you need more to the approach than the methods themselves. You need additionally to chose between them or integrate them.

The best solution is to admit this, and mediate the problem away by inserting 'to use'.

"A popular approach is to use ... methods"

  • It can sound awkward, but 'My favourite breakfast is beans on toast' is totally acceptable. Jul 15, 2017 at 6:41

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