Question

Machines have come and gone, but the spirit of invention lives forever. Which underlined word functions as a preposition in the sentence?

Answer 1

Answer:

The answer to your question would be that the underlined word that functions as a preposition is of.

Explanation:

The only preposition in the sentence above is of. Machines is a noun, have is functioning as an auxiliary verb. Have + come and gone, behaving as the main verbs  form the present perfect tense. Then, but is a conjunction, the is the definite determiner, spirit is a noun as well as invention. Finally, lives is a verb and forever an adverb.

Answer 2

The only preposition in this sentence is the word of.