She was working.
[Function] Subject: She [Category: Noun Phrase] and
[Function] Predicate: was working [Category: Verb Phrase]
Inside this Verb Phrase, was is the auxiliary verb and it takes a Catenative clause as complement. The Cetenative Clause is realized by the Gerand-Participle form of the lexical verb - work. This clause has no explicit subject but it is implied. This Catenative Clause is subordinate to the matrix clause - she was working.
This answers question no. 1
Whether a clause is Canonical or not depends on a number of syntactic features, namely -
- Polarity (Whether the clause is positive or negative - if the clause is positive, it is Canonical and if it is negative, it is non-canonical.)
- Clause Type (Whether the clause is declarative or anything else for example Interrogative or imperative or anything else - if the clause is declarative, it is canonical. Else it is non-canonical)
- Subordination (Whether the clause is subordinate or main clause - if the clause is main clause, it is canonical. And if it is subordinate clause, it is non-canonical.)
- Coordination (Whether a clause is marked by a coordinator or not - Canonical clauses are non-coordinate but non-canonical clauses are coordinate. Ex: That is Bill or I'm blind. Here That is Bill and I'm blind is Canonical but the whole sentence is non-canonical.)
- Information Packaging (Information can be packaged in a variety of ways like PASSIVE, PREPOSING, EXPTRAPOSING etc - Canonical clauses expresses are most elementary ones. If the clause is passive, preposed or extraposed etc, they are non-canonical)
These features can be combined in case of non-canonical clauses.
Ex: Jim says that he is not well.
The canonical clause is Jim says that he is not well, but that he is not well is non-canonical due to two features mentioned above - Polarity and Subordination.
Now in our case
She was working.
It is a canonical clause, but the subjectless Gerund-Participle clause - working - is a non-canonical clause.