Teacher is 5jj .

[notletrest]

Can we say like this :
Teacher is 5jj who has helped a lot of students.
Because I came across the one: "Cantankerous chap Roger always was."
Is the conclusion right? When a noun is put at the beginning of a sentence as a complement of the subject ,the indefinite article before it can be deleted.
Thanks a lot!

[5jj]

Can we say like this :
Teacher is 5jj who has helped a lot of students.

No.

You may hear:
"Helped a lot of students, did X / X did"
"Boring teacher was X /X was."
I don't recommend that you use this informal conversational type of utterance.

[notletrest]

No.

You may hear:
"Helped a lot of students, did X / X did"
"Boring teacher was X /X was."
I don't recommend that you use this informal conversational type of utterance.

You are supposed to mean:
1.Helped a lot of students,did X.
2.Helpled a lot of students, X did.
3.Boring teacher was X.
4.Boring teacher X was.
In my eyes, #3 =(good) teacher is 5jj (who has helped a lot of students.)and from 3#and 4# comes the conclusion when an adjective plus a noun used as the complement if the subject and in the beginning of a sentence ,its indefinite article before the adjective can be deleted.
Is that true?
Thanks a lot!

[notletrest]

No.

You may hear:
"Helped a lot of students, did X / X did"
"Boring teacher was X /X was."
I don't recommend that you use this informal conversational type of utterance.

Dare I ask whether you slipped in giving the sentence "Helped a lot of students, did X/x did."?
I beg your pardon!
Thanks!

[5jj]

Dare I ask whether you slipped in giving the sentence "Helped a lot of students, did X/xX did."?

You may. I didn't