Теория:

Study some information about positive sentences in Past Perfect.
 
Для образования утвердительного предложения в Past Perfect необходимо использовать вспомогательный глагол had и основной глагол в третьей форме (если это неправильный глагол), либо глагол с окончанием -ed (если глагол правильный).
Subject \(+\) had \(+\) V\(3\)/Ved \(+\) other parts of the sentence.
 
              I                  
                                                               had studied
 
       
            you
 
had studied
 
he, she, it
 
had studied
 
we
 
had studied
 
You
 
had studied
 
They
 
had studied
 
 
Examples:
 
Jack had already gone to bed when his parents came home.
  
go to bed.jpg
 
I had cooked pasta and meat by \(6\) o'clock yesterday.
  
pasta.jpg 
Источники:
www.sleep.org/articles/bedtimes-for-kids/
www.thespruceeats.com/bolognese-style-meat-sauce-996171