(a) Как Вы уже заметили, since и for часто употребляются в предложениях с Present Perfect Continuous. Мы используем since для указания момента начала действия:
- She has been watching TV since early morning.
- They have been travelling since last Monday.
For употребляется для указания всего периода времени:
- He has been working in that firm for two months.
- It has been raining for 3 hours.
- They have been agruing about that for more than an hour.
Но с выражениями
all day all morning all week all my life..
НИКОГДА НЕ УПОТРЕБЛЯЕТСЯ for.
- It has been raining all day long.
- She has been training all week long.
(b) Используйте Present perfect (I have done/I have been doing), чтобы спросить или сказать, как долго (how long) что-то происходит (до настоящего момента). Помните структуру How long is it since...?:
- It's two years since I saw your flat.
- It's ages since we visited this place.
- How long has it been raining?
- It's been raining since one o'clock.
(c) Обратите внимание, что с when всегда употребляется Past Indefinite Tense (I did), не зависимо от того, спрашиваете ли вы что-либо или говорите:
- When did he come home?
- When did you see this film?
- He was preparing for his report, when the telephone rang.
- When I entered the room I saw my mother sitting in the armchair.
(d) Помните конструкцию How long is it since?
- It’s two years since I saw your flat.
- It’s ages since we visited this place.