In English, when someone says a sentence in the negative form, such as I don't like sushi or I'm not busy,
you can show that you agree with them in a few different ways by using the words either, and neither.
Let me show you how.
Let's use the example of someone saying, I don't like sushi.
If you want to agree with them and say that you don't like sushi just like they don't like it,
there are a few things you could say.
One option is to say, I don't either.
You keep the same negative don't contraction and just say either afterwards.
I don't either.
Another option is to say neither do I.
It means the same thing as I don't either, but it's a little bit more formal and proper.
In the phrase neither do I, we take the word don't from the original sentence and change it to do.
And then we invert, meaning we put the subject after the verb.
Instead of neither I do, we say neither do I.
So if someone says I don't like sushi, you can agree with them by saying neither do I.
Here's another example of that structure.
If someone says I haven't been to Europe before, you can tell them that you haven't been by saying Neither have I.
In this case, we change the haven't to have, and then we put the subject after the verb.
Neither have I.
Here's one more way you can agree with someone's negative sentence.