"couldn't" "wouldn't be able to" in subjunctive mood

[th.19]

Hello teachers,


I have a question about the usage of "couldn't" and "wouldn't be able to"
in the subjuctive mood.


Without a dictionary, she ______________ solve this problem.


I know that "wouldn't be able to" is can be used, but could "couldn't" be also
used here? Also, if both can be used, is there any difference in the meaning
of the sentence?


Thank you for your help!

[5jj]

There is no real difference in meaning in negative constructions. Both 'couldn't' and 'wouldn't be able to' are possible.

[th.19]

OK --- thank you for your reply!

[philo2009]

Note, incidentally, that neither of these forms as used here would qualify as 'subjunctive', although some more traditional grammarians (such as myself!) would term them forms of the conditional mood.

They would be forms of the past subjunctive only in e.g.

I'd be most grateful if you could help me.

If you would care to follow me, I'll show you to your room.

[5jj]

Note, incidentally, that neither of these forms as used here would qualify as 'subjunctive',...