Nouns: Number

leaves

Step 1: Identify the noun – 'leaf'. Step 2: Check the ending – 'leaf' ends in -f. Step 3: Apply Rule 4 – Most nouns ending in -f or -fe change the -f or -fe to -ves. Step 4: Remove -f and add -ves: 'lea' + 'ves' = 'leaves'. Step 5: 'Leafs' is wrong because this noun follows the -f to -ves rule. 'Leafes' and 'leafe' are not valid forms.

roofs

Step 1: Identify the noun – 'roof'. Step 2: Check the ending – 'roof' ends in -f. Step 3: Remember the exception – Some nouns ending in -f form their plural in the normal way (just add -s). Roof, chief, and gulf are examples of this exception. Step 4: So 'roof' becomes 'roofs', not 'rooves'. Step 5: Always check if a word is an exception to the general -f rule.

mangoes

Step 1: Identify the noun – 'mango'. Step 2: Check the ending – 'mango' ends in -o. Step 3: Apply Rule 3 – Most nouns ending in -o add -es to form the plural. Step 4: So 'mango' becomes 'mangoes'. Step 5: 'Mangos' would be the plural of exceptions like 'piano' → 'pianos', but mango follows the regular -o rule and takes -es.

sheep

Step 1: The question asks for a noun with the same singular and plural form. Step 2: 'Cat' → 'cats' (different forms). Step 3: 'Tooth' → 'teeth' (different forms, changes the vowel). Step 4: 'Knife' → 'knives' (different forms). Step 5: 'Sheep' is correct – both singular and plural are 'sheep'. Other examples include deer, fish, dozen, and aircraft. These are called invariable plurals.