What part of speech is the word 'quickly' in the sentence: 'She runs quickly to the bus stop.'?

What part of speech is the word 'happiness' in the sentence: 'Happiness is important to everyone.'?

What part of speech is the word 'beautiful' in the sentence: 'The garden looks beautiful.'?

What part of speech is the word 'under' in the sentence: 'The book is under the table.'?

What part of speech is the word 'and' in the sentence: 'Tom and Jerry are best friends.'?

What part of speech is the word 'Wow!' in the sentence: 'Wow! That was amazing!'?

What part of speech is the word 'they' in the sentence: 'They are playing outside.'?

What part of speech is the word 'run' in the sentence: 'I run every morning.'?

What part of speech is the word 'softly' in the sentence: 'She sings softly.'?

What part of speech is the word 'book' in the sentence: 'He reads a book every night.'?