Either/neither in a question

[Atari pitfall]

As far as I know, both either and neither are singular quantifiers. It happens I was doing some exercises and this phrase popped into my head:

1. Hasn't either of them fixed the car?

My grammar corrector says that "hasn't" is the wrong form, suggesting:

1. Haven't either of them fixed the car?

Which form is the right one?

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Also, I'd to know how the above sentence sounds and if the following are acceptable:

1. Has neither of them fixed the car?
2. Have none of them fixed the car?

Thank you.

 

[Tarheel]

As far as I know, both either and neither are singular quantifiers. It happens I was doing some exercises and this phrase popped into my head:

1. Hasn't either of them fixed the car?

My grammar corrector says that "hasn't" is the wrong form, suggesting:

2. Haven't either of them fixed the car?

Which form is the right one?

---

Also, I'd to know how the above sentence sounds and if the following are acceptable:

3. Has neither of them fixed the car?
4. Have none of them fixed the car?

I agree with the first one. Also, the fourth one might technically be grammatical, but it seems really odd to me.

 

[Tarheel]

As far as I know, both either and neither are singular quantifiers. It happens I was doing some exercises and this phrase popped into my head:

1. Hasn't either of them fixed the car?

My grammar corrector says that "hasn't" is the wrong form, suggesting:

2. Haven't either of them fixed the car?

Which form is the right one?

---

Also, I'd to know how the above sentence sounds and if the following are acceptable:

3. Has neither of them fixed the car?
4. Have none of them fixed the car?

After looking at it again, I think you could use either one or two. (You would be extremely unlikely to have a reason to use either one.) Number three would work with "either" instead of "neither". Number four still doesn't seem natural to me at all.

Sometimes I like to devise brief conversations to illustrate natural speech. I'll post something if I think of anything.

 

[emsr2d2]

In your first post, there are three different sentences all numbered 1. Can you see how that makes it difficult for us to refer to them in our responses?