Cambridge Grammar of English Hardback with cd-rom a comprehensive Guide

C

S

V

A

a very good book | it | was | too

(non-fronted: it was a very good book too)

Is that so?

By all means

Fair enough

Not at all

True enough

Of course

What a pity!

192 | From utterance to discourse

Cambridge Grammar of English

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However, in spoken English a particular type of structure is common where an

item within the clause structure is placed before the clause and repeated (usually

as a pronoun) in the clause itself. When such an item occurs before the clause, the

structure is called a header:

header

clause

S

V

C

The teacher with glasses, he seems very nice. 

(non-fronted: The teacher with glasses seems very nice.)