Answer:
Mr. William Herring - subject
Is the jolliest man I know - predicate
Step-by-step explanation:
The subject is what the sentence is about.
The predicate tells us what the subject is doing or describes the subject.
The subject of the given sentence is Mr. William Herring. The rest of the sentence, is the jolliest man I know, gives us information about him. This is why that is the predicate.
There are no prepositional phrases in the given sentence. A prepositional phrase is a group of words that consists of a preposition, its object, and words that modify the object. An example of a prepositional phrase is: He is sitting on a chair.