[Grammar] Some problem with "Could have"

[behxrad]

Hi, first I have to thank all of those users who answered my previous questions.

I have some problems in understanding the right meaning of could have and I don't know where exactly to use Could have. I know some examples like,

"I was so tired that I could have slept a whole day".

In this example, I know, it means "I was able to sleep but I didn't".

In another example

"She hasn't come to the party yet, she couldn't have got my message".

In this one, it means "it is possible that she didn't get my message".

I almost have a few problems in using expressions like those in the previous examples and that's okay. But my real problems are when the statements like these in below are expressed and I do not understand which type of could usages they are, whether imagination or something else.

"How could you not have noticed that he had arrested me?".

"As you can see, the tornado almost destroyed everywhere. How could he possibly have survived?".

I don't understand the author's purposes of those questions? why didn't he use past? Please explain what's difference between these examples and those on the top.

I would be so grateful.

 

[bando]

I don't really like the second example. To express the idea that it was possible for her not to have got your message,
I think it would be better to use "might": "she might not have got my message".

 

[Raymott]

"As you can see, the tornado almost destroyed everywhere. How could he possibly have survived?".
I don't understand the author's purposes of those questions? why didn't he use past? Please explain what's difference between these examples and those on the top.

He did use the past. 'Could' in that example is the past tense of 'can'. So present tense would be "How can he possibly have survived."
'Could' has a few meanings:
- as the past tense of 'can'.
- as an indication of possibility for the future. "We could go to the movies tomorrow."
- as an expression of ability in the past. "He could run very fast when he was young."

You should try to check out a few websites, You could start here:
http://learnenglish.britishcouncil.org/en/english-grammar/verbs/modal-verbs/can-or-could
http://learnenglish.britishcouncil.org/en/english-grammar/verbs/modal-verbs/can-could-and-could-have
http://www.onestopenglish.com/suppo...ferences-between-could-and-can/146362.article

 

[Roman55]

In another example

"She hasn't come to the party yet, she couldn't have got my message".

In this one, it means "it is possible that she didn't get my message".

I am not a teacher.

No, in this one it means 'I am pretty sure that she didn't get my message'.

 

[BobK]

He did use the past. 'Could' in that example is the past tense of 'can'. So present tense would be "How can he possibly have survived..."

I wish more ELT teachers thought like this;-). There are zealots in the EFL/ESOL teaching world (such as my tutor when I was a CELTA student) who insist that modals don't have tense. (I may be caricaturing this stance, becase I just don't understand it.)

b