I'm stuck upon a particular example, should we use "do" or "be" in question below:

  • Does it exist?
  • Is it exist?

Thank you in advance!


To make yes/no questions we move the auxiliary verb to the front of the sentence, before the Subject. The verb BE is an auxiliary verb. So we see the following types of sentence:

  • She is happy
  • Is she happy.

Some sentences don't have an auxiliary verb:

  • It exists.

If we need to make a yes/no question here, we need to add an auxiliary verb to make the question. In English if we need to do this we always use the "dummy" auxiliary DO:

  • Does it exist?

There are two types of auxiliary in English. The first group contains the verbs BE, HAVE when used in perfect constructions, and the dummy auxiliary DO. The second group includes the modal auxiliaries. The main members of this group are: CAN, COULD, MAY, MIGHT, WILL, WOULD, SHALL, SHOULD and MUST.

If we already have an auxiliary in the normal declarative sentence, we do not use the dummy auxiliary:

  • She can dance.
  • Can she dance?

Hope this is helpful!

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