How could I know?

[hellokitty]

Here is one of the questions in an exam preparation book.
"Where has she gone?" "How ( ) I know?"
1. could 2. might 3. should 4. would
The book says the answer is 3. should.
I thought both could and should were possible. The book doesn't say the reason "How could I know ?" is wrong. :(
Would you kindly explain to me why?
confused Kitty

[sheena55ro]

Here is one of the questions in an exam preparation book.
"Where has she gone?" "How ( ) I know?"
1. could 2. might 3. should 4. would
The book says the answer is 3. should.
I thought both could and should were possible. The book doesn't say the reason "How could I know ?" is wrong. :(
Would you kindly explain to me why?
confused Kitty

The right answer is "How should I know?"--it means : How am I supposed to know?- it expresses wonder


"Should" expresses :
-advice; suggestion: You should return those books to the library
-duty, moral obligation: You should work a little harder...
-possibility, probability: They should be at home by now.
-wonder, surprise: How should I know?
-criticism: You shouldn`t shout at your mother like that.

"Could" expresses:
-polite request: Could I borrow your pen?
-suggestion : Maybe you could get someone to help you.
-less than 50% certainty : Where is John? He could be at home.

and many others

You should search the web for further details.

All the best,

[hellokitty]

Thank you Sheena55ro for answering my question!

I should say I'm still confused…
The reason why I thought "could" was possible is "could" expresses possibility and "How could I know?" was a kind of rhetorical question like "How could you do such a thing?". (I may be wrong!)

I've just read other thread in this forum and been to an interesting site introduced in it (http://view.byu.edu/), and what I got is:
How should I know --- 42 sentences
How could I know --- 6 sentences
How might I know --- 0
How would I know --- 15 sentences
Does this mean "How would I know?" is a possible answer???

Need help!!!
Kitty

[Tdol]

I think it's a bad question, because you could use 1/3/4 in the answer.
How could/would = it's impossible for me to know
should = it's none of my business to know
I agree with you that 4 is definitely a possibility.

PS Nice to see you're using that site, Kitty. It's worth getting to know the other features, like word + grammatical form, so you can look at things like word + gerund, etc.

[hellokitty]

tdol, thank you very much for helping me!
Your answer cleaned my confusion.
I also thank you for telling us a useful web site and letting me know other interesting functions in the site! I hadn't realized the site had this feature until you mentioned it here. :)
I tried searching "Good luck + preposition" and the result was good to know. I hope it'll help my writing as well.;)

Cheers!
Kitty

[Tdol]

Once you get used to using it, it really helps a lot.