Subject Complement=Predicative Complement?

Question

Hey guys so i just when i think i'm grasping this i get confused i'm reading the Huddlestone an Pullum Introduction to English Grammar and i'm assuming a subject complement is a predicative complement right?
so in the example
This is a clear threat our security
the underlined is a predicative complement or a subject complement and i can prove this by turning it into a passive clause so A clear threat to our security this was doesn't make sense is that incorrect?
So if i wanted to prove something was a predicative complement i could say that pc can have the form of an adjective phrase or that pc can have the form of a bare role np or that pc does not correspond to the subject of a passive clause my problem is i do these things and they don't work like i was just told i can
say "a clear threat to our security this was" and it's okay so that doesn't fall in line to the passive clause rule?

Englishmaven · Accepted Answer

Don't use a passive structure for this. That won't work. You need a transitive verb for that. To check for a complement, switch the subject and the complement. That should work. You may have to change the verb accordingly for number.

I am the teacher.
The teacher is I.

This is a clear threat to our security.

A clear threat to our security is this.

Urribarri · Answer

ok so i could say that i know that a clear threat to our security is a predicative complement because when i swap it with the the subject This the result *A clear threat to our security is this
is ungrammitical??

BillJ · Answer

UrribarriHey guys so i just when i think i'm grasping this i get confused i'm reading the Huddlestone an Pullum Introduction to English Grammar and i'm assuming a subject complement is a predicative complement right?
so in the example
This is a clear threat to our security

Yes, the underlined noun phrase is a subjective predicative complement. Notice that the verb is a form of "be" (see below).

Urribarrithe underlined is a predicative complement or a subject complement and i can prove this by turning it into a passive clause so A clear threat to our security this was doesn't make sense is that incorrect?

Yes, it is incorrect - it doesn't make sense because that's not how passive clauses are formed - for two reasons:

(i) Passive clauses have an active counterpart where there is usually some action performed by a subject on the object of the verb: "The cat chased the mouse", where "cat" is subject and "mouse" is object. In the passive version, the object becomes the subject of the clause and the original subject is either omitted altogether or it appears in a by-phrase: "The mouse was chased by the cat". But in your example, there's no object that could become subject, so a passive is not possible.

(ii) Subjective predicative complements only occur with a certain kind of verb, "be" being the most common - others include "seem", "appear", "become". Importantly, these verbs (sometimes called linking verbs) are not capable of being used transitively (i.e. with objects) which means their complements cannot be turned into passives.

UrribarriSo if i wanted to prove something was a predicative complement i could say that pc can have the form of an adjective phrase

Yes - the crucial feature of a subjective predicative complement is that it can have the form of an adjective (or an AdjP). This is an important way of distinguishing PCs from objects - objects can't be AdjPs.

Urribarrior that pc can have the form of a bare role np

Yes, but the relevance of this is again one of contrast between PCs and objects. A bare role NP (i.e. one that's bare in the sense of lacking the determiner associated with some kind of role, office, or position) can be a predicative complement, but an O can't: "She became supervisor" (PC) is fine, but there's no *"She knew supervisor".

Urribarrior that pc does not correspond to the subject of a passive

Correct - that's a crucial point about PCs.

Urribarrimy problem is i do these things and they don't work like i was just told i can
say "a clear threat to our security this was" and it's okay so that doesn't fall in line to the passive clause rule?

They don't work because you're not following the grammatical rules for forming passives, as I've outlined above, and that's why you end up with ungrammatical sentences like *"A clear threat to our security this was".

Does that help?

BillJ

Urribarri · Answer

it certainly did help me thankyou ever so much *** i feel so silly sometimes well at least i know this now

Subject Complement=Predicative Complement?

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