Question Formation Steps

Original Sentence:

They sang songs.

Step 1: Add 'did'

Did they sang songs?

Step 2: Change verb to base form

Did they sing songs?

Question Pattern:

graph LR A[Did] --> B[Subject] B --> C[Base Verb] C --> D[Rest of sentence] D --> E[?]

Past Simple	Base Form	Question
wrote	write	Did he write?
sang	sing	Did they sing?
had	have	Did you have?