This document provides an overview of the key grammar topics covered in English Week 4, including the indefinite article a/an, prepositions of time and place, adverbs, countable and uncountable nouns, and question tags. It explains that "a" is used before singular countable nouns beginning with consonant sounds, while "an" is used before singular nouns beginning with vowel sounds, and that "some" is used instead of a/an with uncountable nouns and plural nouns.