I have recently read this article and stumbled across this:
The policeman seemed to be very annoyed.
He seemed to be a very annoyed policeman.
According to the site, the first one is correct and not the second one. Why is that? To me they both convey the meaning of the policeman being annoyed. Also, what is the difference between the two sentences.
The 'rule' at the site you link to is expressed too generally.
What it should say is:
We do not say
He seemed to be a very annoyed policeman.
when what we mean is
The policeman seemed to be very annoyed.
The difference in the two sentences lies in the discourse context. Before a sentence is uttered, the hearer or reader already has some information about the context. The sentence adds new information to what the hearer already knows.
In the construction Subject + Predicate, the Subject is typically old information, and the Predicate is new information. When the predicate has the form LinkingVerb + Complement, the Complement slot is where we put the new information.
In the sentence The policeman seemed to be very annoyed, The policeman is old information. We already know who the policeman is—you know that even without the preceding context because he is identified with the. The new information which the sentence gives us is the policeman's attitude: very annoyed.
But in the sentence He seemed to be a very annoyed policeman, the old information is he—again, you know that even without the preceding context because he is identified with the pronoun he. The new information is the noun phrase a very annoyed policeman. The new information which the sentence gives us is the man's profession, policeman, along with the fact that he is annoyed.
The second phrase is a perfect reasonable answer to: Who's that crazy man running down the street screaming at everyone? Answer: He seems to be a very annoyed policeman.
Prescriptive grammars, such as those set forth by organizations like The British Council are a futile attempts to ossify a living, breathing language. They're good as a firm structure upon which to build, but at the edges they become too rigid and inevitably pedantic.
