Narrative verb form: Past Perfect Continuous

Please, visit the following websites to find an explanation about the use of the past perfect continuous verb form.

1. PAST PERFECT CONTINUOUS: How to use it.
2. More examples on how to use this verb tense.
3. http://www.englishtenses.com/tenses/past_perfect_continuous

Exercises

1. http://www.englishgrammarsecrets.com/pastperfectcontinuous/menu.php
2. http://www.e-grammar.org/past-perfect-simple-continuous/
3. http://learnenglish.britishcouncil.org/en/english-grammar/verbs/past-tense/past-perfect
4. autoenglish.org/past perfect continuous
5. Past-perfect-progressive-exercises
6. fdslive.oup.com
7. cambridge.org/grammarandbeyond/wp-content/uploads/2012/02/Grammar_and_Beyond_Student_Book_3_Unit_4.pdf