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

modal

aux

B: Yes, we should have.

modal aux

aux

They 

must have been talking about it for ages. 

modal

aux

aux

aux

It 

might have been being used at the time. 

Where there are combinations of modal verbs and auxiliary verbs, the order of

these is modal verb ➛ perfect have ➛ progressive be ➛ passive be ➛ lexical verb:

modal      perfect progressive

passive  lexical verb

It 

might have    been       being      used

at the time. 

Each element requires a particular kind of complementation to follow it:

a The modal verb must be followed by the bare infinitive (without to).

b The perfect have must be followed by the -ed participle.

c The progressive be must be followed by the -ing form.

d The passive be must be followed by the -ed participle.

Û

217–226 The verb phrase 2

304 | Introduction to word classes and phrase classes

Cambridge Grammar of English

---

Auxiliary do is required to form negatives, interrogatives and emphatic forms

when the lexical verb is not preceded by any other auxiliaries:

She 

doesn’t smoke.

(negative)

Did you buy a newspaper?

(interrogative)

I 

do like your skirt.

(emphatic)

The verb phrase (in bold below) begins the predicate part of the clause (in green

below). This is the part which elaborates what the subject is, does or experiences: