Past Perfect Continuous

https://www.youtube.com/watch?v=88L7ErhfLFQ

Form:     had + been  + verb  + -ing

 

     I had been waiting there for two hours before she finally arrived.

     She had only been studying English for two years before she got

     the job.

     

     note :

*  When you are using a verb tense with more than one part

    such as Past Perfect Continuous (had been studying),

    adverbs often come between the first part and the    

    second part : had only been studying