Согласно Конституции РФ, высшим органом исполнительной власти является Правительство РФ Государственный Совет

1) When she came to the station, the train has already left.

2) We were very pleased to see Ann again. We haven't seen her for three years.

3)Tim has already done his work when his mother phoned him.

Просто когда переделываешь предложение в пассивный залог опускаешь время на ступень ниже. Например, с present simple на past simple => past perfect

will => would