No. An infinitive is to plus a verb.
Study this page. It has your answer.
http://www.chompchomp.com/terms/phrase.htm
Identify the phrase in parenthesis in the sentence.
The idea of alien life, (proposed many years ago), has not yet been proven.
prepositional
participal
gerund
infinitive**
I thought it might be an appositive, but now I'm not sure. I'm guessing it is D?
6 answers
Oh okay! So it is a prepositional phrase, right?
My you learned a lot in less than 5 minutes. Which is the preposition?
The site said that the preposition was explaining the "which one" question which would give more information on the topic. So in this case, asking the question 'which one?' would be like this: Which idea of alien life? The one "proposed many years ago". At least that is the way that I think it might be seen?
You misread that site. A prepositional phrase begins with a preposition and ends with a noun or pronoun.
I called my teacher and we agreed that it was participial. Thank you Ms. Sue! :)