Which is correct?:
A and B combined is sufficient
or
A and B combined are sufficient.
…Basically, is the proper interpretation of 'A and B' as two nouns or 'A and B combined' as a single noun?
grammarword-choice
Which is correct?:
A and B combined is sufficient
or
A and B combined are sufficient.
…Basically, is the proper interpretation of 'A and B' as two nouns or 'A and B combined' as a single noun?
Best Answer
In terms of meaning, if you use the singular verb with "A and B combined," you are suggesting "A and B combined" should be viewed as a single entity, like "the set A and B." If you use the plural verb, you are suggesting "A and B" should be viewed as at least two things, A and B, which are combined.
In terms of usage, I did a search on COCA to see what I could turn up. I imposed a couple of commonsense restrictions: A and B both have to be singular elements (or I'd always expect are), and the noun phrases joined by a conjunction have to be the primary subject (so nothing like "sales of A and B combined are..." which relegates A and B to a prepositional phrase modifying sales).
I found three results for combined are:
Here are the results for combined is:
I can't detect a significant difference in frequency from that sample. The usage really seems to vary based on how the writer is thinking of A and B combined, and not based on a universal rule. Is may be more common in a caption or headline (as the excerpt from the Saturday Evening Post appears to be), or if it's clear the resulting item is a single thing ("a pre- and pro-biotic combined" is a "synbiotic," a single thing.