Past Simple vs. Past Perfect

Простое прошедшее - Прошедшее совершенное

Past Simple используется 

- для выражения событий, которые произошли и закончились в прошлом (I lost my key yesterday. Tchaikovsky was a great composer. He wrote many pieces of music.

Слова-помощники: yesterday, last week/month/year, two days/weeks/months/years ago

Past Perfect используется, чтобы описать действие в прошлом, которое произошло раньше другого действия в прошлом: When John arrived at the party, Kate had already gone home.

examples

My brother had never done any sport before he took up basketball.

Before last night I hadn't spoken to my mum for a month.

What had Josh done that you became so angry?

Lisa had left before the party even started.

What had they said that made you so upset?

Had the snowstorm started before you left?

I had never driven a Ferrari before I went to Monaco.

Mary explained that she had just come back from her holidays.

Samanta had never danced salsa before she went to the class.

I announced that I had left my job.