modal perfect

[aysaa]

Hello,

I have read that we can't construct a modal perfect sentence with 'can have' except 'can't have'.

She can't have killed her friend. (That's ok)

My question is can we construct a modal perfect question (negative or positive) sentence with
'can have' ?

-Can she have killed her friend?

-Can't she have killed her friend?

Thanks...

 

[emsr2d2]

Hello,

I have read that we can't construct a modal perfect sentence with 'can have' except 'can't have'.

She can't have killed her friend. (That's ok) - Yes, that's OK if you mean that it is a physical impossibility that she killed her friend.

My question is can we construct a modal perfect question (negative or positive) sentence with 'can have'? No.

-Can she have killed her friend?
Could she have killed her friend?

-Can't she have killed her friend?
Couldn't she have killed her friend?

Thanks.

See above.