Hidden do

From Teflpedia

Hidden do is a feature of the syntax of English that means the auxiliary do can be, and usually is, "hidden" in certain sentence forms.[1]

For example the sentence "I eat pizza" (without "do") is syntactically equivalent to "I do eat pizza" (with "do").

If present, do takes grammatical markers for tense and number, and the main verb reverts to the base form.

Type Without do With do Notes
Present simple I/you/we/they eat pizza I/you/we/they do eat pizza
3rd person singular, present tense He/she eats pizza He/she does eat pizza Marked with third person -s
past tense He/she ate pizza He/she did eat pizza Marked for past tense
Wh- question (present tense) Who writes those books? Who does write those books? We can only do this with wh- questions with who, what, which and whose.
Wh- question (past tense) Who wrote those books? Who did write those books?
  1. There may be a more formal name for this