This book covers the following topics: English grammar - 'do' - structure - a - affirmative, structure - b - negative, structure - c - interrogative, structure - d - short answers | English grammar - 'does' - structure - a - affirmative, structure - b - negative, structure - c - interrogative, structure - d - short answers | English grammar - 'did' - structure - a - affirmative, structure - b - negative, structure - c - interrogative, structure - d - short answers | Exercises || 'Do' and 'Does' are used in present tense while 'Did' is used in past tense. Verb 'Do' is used as an AUXILIARY VERB as well as a MAIN (ORDINARY) VERB