Question

Preschool children learn and apply syntax rules. the grammatical error we observe in the question "when we are going outside?" is an example of difficulty with mastering

Answer 1

The answer would be Subject–auxiliary inversion. It encompasses putting the subject after a finite auxiliary verb, instead of before it as is the circumstance in usual declarative sentences. The auxiliary verbs which may contribute in such inversion are is, can, have, will, etc. are labelled at English auxiliaries and contractions. A usual example of subject–auxiliary inversion is given:

a. Luis has read the book. - Statement

b. Has Luis read the book? - Yes–no question formed using inversion

Answer 2

The grammatical error we observe in the question "when we are going outside? is an example of difficulty with mastering subject-auxiliary inversion or also called subject-operator inversion. (ANSWER)

Subject-auxiliary inversion is a type of inversion in English where a finite auxiliary verb inverts or change places with the subject. The correct word order would be Auxiliary + Subject and not differently. We see in the question os study how it is the other way. The correct way to ask that question would be: "When are we going outside?"