My best friend, John is an actor.

[sadra1400]

Let's look at the following sentences.

1- My best friend, John is an actor.
2- My best friend, John, is an actor.
3- John, my best friend, is an actor.

question1: I know the third one is correct, but I don't know which one is correct, 1 or 2, or both. Should there be a comma after "John"?
question2: in the third sentence, "John" is subject, and "my best friend" is an adjective phrase. What is the subject if the second one is correct? John or my best friend? And what is the adjective phrase in the second one?

 

[jutfrank]

Sentence 1 shouldn't have a comma.

Both phrases my best friend and John are noun phrases, not adjective phrases.

 

[sadra1400]

Sentence 1 shouldn't have a comma.

Both phrases my best friend and John are noun phrases, not adjective phrasth

Is not "my best friend" an adjective phrase in the third one?

 

[5jj]

The headword of my best friend is friend. a noun. So, the whole phrase is a noun phrase.

 

[sadra1400]

The headword of my best friend is friend. a noun. So, the whole phrase is a noun phrase.

But "my best friend" describes "John" in the third one, and we can remove it from the sentence. John is the subject, and "is" is the verb.
our headword is "John".
Are my assumptions wrong?

 

[5jj]

My best friend is an appositive phrase; It does not describe the subject; it clarifies/expands it.

 

[Tarheel]

But "my best friend" describes "John" in the third one, and we can remove it from the sentence. John is the subject, and "is" is the verb.

You could argue that "My best friend" is the subject. (Take out "John" and the sentence still makes sense.)