Present cont or perfect cont
He (begin) to write his composition at three o'clock. It's already eleven, and he still (to write) it. He says (to finish) it by twelve,
Правильные ответы: began, is still writing, will have finished.
Вопрос: почему не has still been writing. Согласно правилу: "Действие, которое началось в прошлом (в данном случае 3:00 p.m.), продолжалось в течение некоторого времени и все еще продолжается в момент разговора (11:00 p.m.)".
Если б там не было it is eleven. Момент дан.В этот момент он делает.
Правильные ответы: began, is still writing, will have finished.---Совершенно правильные ответы.
Вы рассуждаете неправильно. Ваши рассуждения применительны к PRESENT PERFECT CONTINUOUS TENSE. Только не надо употреблять с этим временем маркер STILL. Он употребляется с другим временем, то есть PRESENT CONTINUOUS, что они и дают в ответах.
Вот если бы в предложении было сочетание с предлогом FOR (for two hours) или SINCE (since 3 o'clock), тогда другие дело. He has been writing it for two hours already and has not finished it yet. He has been writing it since 3 o'clock and has not finished it yet.
Still не сочетается только с Perf. cont. или же с перфектом в целом? А если привести такой пример I still haven't bought the tickets? По-моему это даже равнозначно I haven't bought the tickets yet. Другое дело, континиус:
I have still been doing my stuff since morning. Звучит ли здесь это тафтологично, как если бы сказать Earlier I used to play the piano in my childhood, мол сама конструкция сама за себя говорит, что ты до сих пор в процессе? Emphasizing is prohibited?
from English Grammar Today
Still is an adverb and an adjective.
Still as an adverb
We use still as an adverb to emphasise that something is continuing:
They have been together for 40 years and they are still very much in love.
We’re still waiting for our new couch to be delivered.
We usually put still in the normal mid position for adverbs (between the subject and the main verb, or after the modal verb or first auxiliary verb, or after be as a main verb):
She still goes to French classes every week. (between subject and main verb)
He’s still studying. (after the modal verb or first auxiliary verb)
I’m still hungry. (after main verb be)
In informal speaking, you will often hear still used in end position. Many speakers of English may consider this usage too informal:
I can’t find my bag still. Has anyone seen it?
Have you got their address still?
The opposite of still is no longer, not any longer or not any more:
Are you still teaching in Birmingham?
No, I’m not working there any more (or any longer). (or No, I’m no longer working there.)
Not: I’m not still working …
We sometimes use still to show that the continuing situation is not desired or is surprising, especially when still is stressed and in a negative clause. Note the position of still before the auxiliary or modal verb when we use it in a negative clause:
She bought a car two months ago and she still hasn’t taken any driving lessons. (still is stressed)
I still can’t find Kay’s phone number. (still is stressed) (I’ve been looking for it for a long time. I wish I could find it.)
We can also use still stressed in this way for something that is true in spite of other things:
We offered £350,000 for the flat but they still wanted more.
We were near the front of the queue but we still didn’t get tickets for the concert.
We can use still in front position to mean ‘on the other hand’ or ‘nevertheless’:
I don’t really like weddings. Still, I’ll have to go or they’ll be offended.
… there was not one air-conditioned room on the tour and there were not enough minibuses for all the passengers. Still, I did manage to get into one minibus but it broke down on the way to the hotel.