We are experiencing some confusion with Chapter 10, where we are learning that noun clauses can be objects of prepositions. We are also adding some prepositions to our list that were previously only subordinating conjunctions, i.e., "as" and "when".
My question is:
How can you tell the difference between an adverb clause and a prepositional phrase with a noun clause as its object when so many words may be either subordinating conjunctions (i.e., part of an adverb clause) or prepositions (see pages 484 and 517)? Several examples in the written exercises and worksheets look like they might be prepositional phrases with noun clause objects when the answer key says that they are not.
I searched online for the answer and was only able to find one video that was somewhat helpful. It said that noun clauses may be objects of the following prepositions: for, about, on, in, to, and from. To me this implies exclusivity, so other prepositions can't have noun clauses as objects?
The video also said that the clause must have these pronouns as subjects: what, why, when, how, who, whom, whoever, whomever. This later suggestions is even more confusing to me because whom and whomever are objective pronouns, not nominative pronouns. So how can they be subjects of clauses?
I think I'm getting a vague understanding that the prepositional phrase with a noun clause object must contain BOTH a preposition AND an introductory word (from page 209). However, an adverb clause only contains one such word. Is that right?
Any assistance would be much appreciated.