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Past Perfect Progressive (continuous)-Past Perfect
Past Perfect Progressive (continuous)-Past PerfectThe Form of the tenses??!!
Bibliography
![Reichenbach's Theory of Tense and it's application to English · [+past] sang simple past [+past] was singing past progressive [+past] had sung past perfect [+past] had been singing](https://static.cupdf.com/doc/110x72/5e2c3edf345b3d33a77b41c2/reichenbachs-theory-of-tense-and-its-application-to-english-past-sang-simple.jpg)
![Past Perfect Progressive & Future Perfect Progressive Part 2[1]](https://static.cupdf.com/doc/110x72/55cf92fe550346f57b9aff35/past-perfect-progressive-future-perfect-progressive-part-21.jpg)
