Learn English – “If anyone knows” or “Does anyone know”

verb-forms

I am a native English speaker who is living abroad and as such I get many questions about English that I find hard to answer having never studied English grammar.

One of them is the following:

  • Does anyone know
  • If anyone knows

Why does the verb "to know" change depending on whether the question starts with "does" or "if"?

Best Answer

According to English grammar, if an auxiliary verb ("to do", in this case) is present, it is the only one that conjugates, while the main verb remains in the bare infinitive form.

The sentence with "if" does not have an auxiliary verb, so in that case the verb "know" conjugates; while in the sentence with "does", "know" stays in the infinitive form. Consider:

Anyone knows; if anyone knows; maybe anyone knows;
Anyone does not know;
Does anyone know?;
Anyone does know;

Although the form "subject + does + verb" is not popular, it is pretty grammatical. This form is principally used to emphasize a fact, particularly to contradict a previous assertion, with emphasis on "does":

"I don't think anyone knows."
"This can't be. Someone does know!"*

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