Past Perfect tense

определённого момента в прошлом. Этот момент может быть определён:
такими обозначениями времени, как
by 5 o`clock (к 5 часам); by Saturday (к субботе); by the end of the year (к концу года); by that time (к тому времени); by the 15th of December (к 15 декабря)
By the end of the year he had learnt to speak English.
We had done our homework by 4 o`clock.
другим (более поздним) прошедшим действием, выраженным в Past Simple:
We watched the film which our friends had told us about.
Tom ate an ice-cream he had bought in the shop.

того, как):
After the sun had set, we decided to return home.
в сложно-подчинённом предложении с союзом before (прежде чем; до того как):
I had finished my work before my mother came.
в главном предложении при наличии наречий
hardly, scarcely (едва):
He had hardly entered the house, when it started to rain.

she written the composition by 3 o`clock?
- She had not written the composition by 3 o`clock.

a lot about it.
I found that your country (to change) so much.
I (to hear) that Moscow became as an international city as London.
I (to expect) that Russia is a cold country and I (to find) it was true.
She (to be born) before the war (to begin).
Captain Cook (to discover) the island before he (to die).