He wouldn't have done that!

[yi-ing]

A: I'm sure he stole the money.

B1: No. He couldn't have done that!
B2: No. He wouldn't have done that!
B2: No. He mightn't have done that!


May I ask the difference between B1,B2 and B3?

 

[Raymott]

Why not tell us what you think they mean first?

 

[yi-ing]

Why not tell us what you think they mean first?

I just know that the first one probably shows that "it is impossible for him to steal the money."
I have problem with two others and I have no idea if all of them are conditional sentences or not!

 

[jutfrank]

B1 and the first B2 are correct. The second B2 (B3) is incorrect.

They are not conditional sentences. They simply express the speaker's speculation that 'he' did not do whatever it was.

With (the first) B2, the speaker is probably saying that he/she knows the person in question (referred to as he) well enough to be reasonably confident of being able to predict that person's behaviour, and that given this understanding, it is reasonable for the speaker to conclude that the person in question did not do whatever it was it has been claimed that he has done.

(I'm sure there's a shorter way of saying that!)

 

[yi-ing]

Thanks so much. I'm so sorry for a typo in naming the sentences (two B2s) and have caused the problem!

So, we don't have this structure "He might not have done that" in English? Or is it just incorrect in this context?

Do you think which one is stronger in showing that someone is impossible to do something? B1 or B2(THE FIRST)

 

[jutfrank]

I'm so sorry for a typo in naming the sentences (two B2s) and have caused the problem!

Okay, but please be extra careful of this in future.

So, we don't have this structure "He might not have done that" in English? Or is it just incorrect in this context?

That's also correct (whereas with the contracted form mightn't it isn't), but with a different meaning/use.

Do you think which one is stronger in showing that someone is impossible to do something? B1 or B2(THE FIRST)

B1 is stronger in that sense than B2.

 

[Tdol]

So, we don't have this structure "He might not have done that" in English? Or is it just incorrect in this context?

You could use might not have when you don't know for sure.

 

[teechar]

So, don't we [STRIKE]don't[/STRIKE] have [STRIKE]this[/STRIKE] the structure "He might not have done that" in English? Or is it just incorrect in this context?

We do. For example, consider the following dialogue between two police officers.

A: I think we should arrest Mason. He has "guilty" written all over his face.
B: I'm not so sure. He might not have done it. I believe Nelson is our man.