Modals: Logical Conclusion/Inference and Negatives

[kongo09]

If I am not mistaken, dolphins are whales anyway (but not fish)

kongo09

[mayaly]

I also think that "they" is missing here. But, Emo, why do you think that the anwer is B?

[The Iconoclast]

Sorry to resurrect an old thread, but :

"could have done it" (possibility)
and
"could NOT have done it" (logical conclusion)

"I could have done it" = "There is a possibility that I have done it." (If something is possible, it may or may not happen. "There is a possibility that we will not have school tomorrow because of heavy snow.")
"I could NOT have done it" = "There is NO possibility that I have done it." (If something is NOT possible (impossible), there is NO way it will happen.)

Maybe that would help.

On a side note, let's not forget Arnold Schwarzenneger's (spelling?) quote :

"To those critics who are so pessimistic about our economy, I say, Don't be economic girlie men!" –at the Republican convention

[somu]

Good work guys !