Final answer:
The plural forms of the given words are 'children', 'feet', and 'people'.
Step-by-step explanation:
The plural form of the word 'child' is 'children'. Therefore, the sentence should be: 'The children come to the park.'
The plural form of the word 'foot' is 'feet'. Therefore, the sentence should be: 'Your feet have grown; you need new boots.'
The plural form of the word 'person' is 'people'. Therefore, the sentence should be: 'Many people will attend the show.'
Learn more about Irregular plural nouns