this / that / these / those & plurals

We use demonstrative pronouns and adjectives to point at things. 'This' points to one thing close to you, and 'that' points to one thing far away. When there is more than one thing, we use 'these' for things that are close and 'those' for things that are far away. The rule is simple: 'this' and 'that' go with singular nouns, while 'these' and 'those' go with plural nouns. To make most nouns plural, you add -s (book → books, pen → pens). Nouns ending in -s, -sh, -ch, -x, or -z add -es (box → boxes, watch → watches). Some nouns have irregular plurals that you must learn by heart: man → men, child → children, foot → feet, mouse → mice. You must always match the demonstrative to the noun — if the noun is plural, do not use 'this' or 'that'. For example: 'This book is mine, but those books on the shelf are my sister's.'