Adverb
It is a verb.
The word 'in' would be a preposition in the example sentence you gave.
Girlfriend is a noun.
How to use the word in a sentence.
onomatopoeia
it depends what word it is it could be any part of speech depending on the sentence
What "part of speech" is the word "said?"
The word beautiful is an adjective. The word behind is a preposition.
The word sentences is a noun. It is the plural form of sentence.
The term for knowing a word's part of speech in order to appropriately use it in a sentence is "word-usage."
It is a verb.
By use of the word in a sentence.
A word is a part of speech, not a sentence like the one in your example.
The use of the word in the sentence derminates the part of speech
The word 'this" in the sentence is an adjective describing book.
it is an English speech
The word 'in' would be a preposition in the example sentence you gave.