Take the simple sentence "It is almost perfect."

The subject is ‘It’. The predicate is ‘is almost perfect’. The complement is ‘almost perfect’. The copula is ‘is’. ‘Almost’ is the adjunct (part of the sentence that modifies the verb) and ‘perfect’ is the predicative adjective modifying the expletive ‘it’. ‘Almost’ modifies ‘perfect’ and is the predicative adjunct. ‘Perfect’ modifies the subject ‘it’ and hence ‘almost’ is a predicative adjunct to the subject.