A sentence that tells us something is a statement. If the sentence is in the simple present or simple past tense, it can be changed into a question by using do, does or did as the first word.

• John likes painting. (Statement)
• Does John like painting? (Question)
• I make models from clay. (Statement)
• Do I make models from clay? (Question)
• The boys practise cricket everyday. (Statement)
• Do the boys practise cricket everyday? (Question)
• They played well yesterday. (Statement)
• Did they play well yesterday? (Question)

Notes
Do is used in the present tense when the subject is a plural noun or a plural pronoun (we, they, you). Do is also used with I.

Does is used in the present tense when the subject is a singular noun or pronoun (he, she, it).

Did is used in the past tense with both singular and plural subjects.

Related posts:

1. How to change a statement into a question
2. The Sentence