by the time какое время

Ответ от Sky[гуру]
Слова-показатели и примеры употребления в основных видо-временных формах активного залога:
Present SIMPLE:
(Usually, always, often, every day, seldom, never)
Я часто пишу ей
I often write to her
Past Simple:
(Yesterday, last (week), ago, in 1999)
Я написала ей письмо вчера
I wrote a letter to her yesterday
Future Simple:
Tomorrow, next (week), in future, in 2052, some day
Я напишу ей письмо завтра
I will write a letter to her tomorrow
Present CONTINUOUS:
(now, at this very moment, right now. Listen! Look!)
Я пишу ей письмо сейчас
I am writing a letter to her now
Past Continuous:
(at… o'clock; when smb did smth; while smb was doing smth)
Я писала письмо, когда мама пришла
I was writing a letter, when my mother came
Future Continuous:
(tomorrow at… o'clock; from 3 till 5 o'clock)
Я буду писать письмо завтра с 3 до 5
I'll be writing a letter tomorrow from 3 till 5 o'clock)
Present Perfect:
(just, yet, already, ever, never, recently, today, this week, this month)
Я только что написала это письмо
I have just written this letter
Past Perfect:
(by… o'clock yesterday; before; when)
Я уже написала письмо, когда он пришел
I had already written the letter, when he came
Future Perfect:
(by… o'clock tomorrow; by this time tomorrow)
Я уже напишу это письмо завтра к 3 часам
I will have written this letter by 3 o'clock tomorrow
Present Perfect Continuous:
(Since 5 oc'lock, since childhood; for 2 hours, for 10 years, for a long time, all my life)
Я пишу это письмо уже 2 часа (и еще буду писать какое-то время)
I have been writing this letter for 2 hours.
Past Perfect Continuous:
(Since / for)
Я писала письмо 2 часа вчера
I had been writing a letter for 2 hours yeasterday.
Future Perfect Continuous:
(Since, for, by the time, next week, by the end of the year)
Я буду писать это письмо завтра уже 3 часа к этому времени)
I will have been writing this letter for 3 hours by this time tomorrow
Источник: Преподаю английский