Post History

## Do Support

Let's see exactly where the sentence comes from. There are two processes going on here, ["do support"](https://en.wikipedia.org/wiki/Do-support) and ["inversion"](https://en.wikipedia.org/wiki/Subject%E2%80%93auxiliary_inversion).

The full, standard non-question sentence is, of course, "Using the plural form for a singular object makes sense." In "title-ese", of course, we tend to drop such things as the articles 'the' and 'a', and I will do so here as well to match the title in question.

In older English, we could directly invert it to form a question, i.e. "Makes using plural form for singular object sense?" However, in modern English, non-modal verbs are forbidden to undergo inversion. How can we form a question then? Using "do support": we use and invert the helping verb "do" (inflected as necessary).

Original Sentence | "Using plural form for singular object makes sense."
-----|-----
Do support | "Using plural form for singular *does make* sense."
Plain inversion (archaic) | "Makes using plural form for singular object sense?"
Do support + Inversion | "Does using plural form for singular subject make sense?"

## Comparison with 'is'

Usage of 'is' is the continuous form. Notably, in your case, the present continuous (though you didn't inflect "make").

Original Sentence | "Using plural form for singular object makes sense."
-----|-----
Present continuous | "Using plural form for singular is making sense."
Present continuous + Inversion | "Is using plural form for singular subject making sense?"

While not grammatically incorrect, this would be strange to say because it uses the present continuous, that is, you are asking if it makes sense *at the moment*, not in general. With the 'do' construction, we are asking generally, which fits better in this context - a sentence making sense does not rely on the time.

Let's illustrate this with another sentence where the two constructions both make sense, but mean different things:

Original Sentence | "He smiles."
-----|-----
Present continuous | "He is smiling." (right now)
Present continuous + Inversion | "Is he smiling?" (right now)
Do support | "He does smile." (There are times when he smiles)
Do support + Inversion | "Does he smile?" (Are there times when he smiles?)