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hello,

could you please explain when i use the past perfect, when i use the past perfect continuous and the simple past? I never know when i have to use each case.
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Comments  (Page 3) 
2. While he had been reading the book, his uncle came back

This sentence is nonsense

While he was reading the book, his uncle came back

This already suggests the commencement of reading occured before uncle came home and was interrupted.

Past Perfect tenses are not really necessary when "before" or "after" is used as this clearly marks what happened first.