Past Perfect

Annotations:

• https://www.quora.com/What-is-the-subject-in-a-sentence The subject is the entity of a person, place or thing doing the action in a sentence.

Annotations:

• https://www.thoughtco.com/english-grammar-past-auxiliary-verbs-1211113 The auxiliary ver had is used in positive and negative senteces, as well as in questions. 

Annotations:

• https://writingexplained.org/grammar-dictionary/past-participle A past participle is formed from a verb and modifies a noun.

Annotations:

• https://dictionary.cambridge.org/grammar/british-grammar/about-words-clauses-and-sentences/complements A complement is necessary in order to complete a meaning.