questions on 'can' vs 'am (is, are) able to' & Passive Voiceъ

[nata_dtw]

Hallo,
Would anyone be so kind as to answer my questions?
1) We normally use 'can' and 'could' to express general meaning, 'be able to' in the meaning 'manage' in a specific situation. It's clear. What is the difference between 'can' and 'be able to' in the Present? I asked this question but got answers like 'they are almost identical'. I would like to know how the sentences 'He can drive a car' and 'He is able to drive a car' differ.
2) All English grammar books written in Russia say that the Passive Voice is never used in Perfect Progressive Tenses, that is what they call the basics. On one site I've read that sentences like 'The car has been being washed for 2 hours' are also possible. Is that really so? When I searched this in Google, there were not so many examples. Where is the truth?
Thank you, Natalia

[BobK]

Hallo,
Would anyone be so kind as to answer my questions?
1) We normally use 'can' and 'could' to express general meaning, 'be able to' in the meaning 'manage' in a specific situation. It's clear. What is the difference between 'can' and 'be able to' in the Present? I asked this question but got answers like 'they are almost identical'. I would like to know how the sentences 'He can drive a car' and 'He is able to drive a car' differ.
2) All English grammar books written in Russia say that the Passive Voice is never used in Perfect Progressive Tenses, that is what they call the basics. On one site I've read that sentences like 'The car has been being washed for 2 hours' are also possible. Is that really so? When I searched this in Google, there were not so many examples. Where is the truth?
Thank you, Natalia

1) I can drive a car. It's an ability I've had since November 1970. But a week before a teacher training course I started in 2004 I had a cycling accident - which meant that I wasn't able to drive. But the difference is very slight; after the accident, feeling the world was against me, I might have said 'I can't drive' - in a fit of self-pity. My wife might have said 'Don't be silly, of course you can. You're just not able to use reverse'. It's all a matter of nuance.
2) I can't say I agree with those books. I would agree that the Passive voice is used less often than the Active voice (in all tenses), that the Perfect Progressive tenses themselves are rare, and when you put those two rare things together you get something that's extremely rare. But this is quite possible: "I just rang the mail-order people, and they said my order is still being processed. I told them it's been being processed for two months now, and I want my money back."



[Incidentally, 'Where is the truth?' sounds a bit metaphysical! It would have been better to ask 'Which [one] is true?]

b