Since I see this is a bit of a homework question type, I will not only answer it, but make sure you understand what's what. Bear with me, okay?
"The average cow spends eighteen hours a day chewing."
"average" is an adjective for "cow", which is your subject. There's your answer. Now, please keep reading quickly.
"spends" is the verb, which tells that the cow spends...What? "hours" How many? "eighteen", which is an adjective for "hours". How? Because "hours" is a direct object, or a noun that the verb talks about.
I apologize for sounding so silly explaining the basics. It wanted to make it more of a learning reply.
if you reframe the sentence, you will get the complete subject: "trouble develops on the safari." the complete subject is "trouble."
"Man" is the subject, "is" is the verb.
The complete subject of this sentence is "The cat." Everything from "purred" on is part of the predicate. The cat did what? Purred. How? With pleasure. At what? At the visitor's skill.
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You can make a sentence with any number of words. Typically, a sentence has subject and predicate; ie subject & verb & object. "Cats kill birds" (Three word sentence) But some verbs are intransitive (i.e take no object): "Philosophers think". (Two word sentence) Some questions may be orders, with or without implied words; "Attention!" = "You, stand to attention!". "Go!" = "You, go!". (Two word sentence) Some questions may be questions, with or without implied words: "Why?" referring to words from a previously uttered sentence. *None of those sentences have eighteen words, but that total number is actually not a very high one.
A subject in a sentence is who, what, or where the sentence is about.
The subject is who or what the sentence is about.
A subject is what the sentence is about.To make a sentence with a subject think like if it was a theme.
The subject in the sentence is "you."
What is the subject of this sentence? She was the subject of an investigation.
The subject tells who or what the sentence is about.
Does a sentence need a subject?
Who or what the sentence is about is the subject of the sentence.
Who or what the sentence is about is the subject of the sentence.
The subject of a sentence is who or what that sentence is about.
A sentence missing a subject or a verb is a fragment.