When using Indefinite Pronouns, the verb is in the "3rd personal singular" form.
When adding a Tag Question, we invert the sense of the verb (+ to – and – to +).
So, it's OK to say:
Somebody is there, isn't it?
Nobody has arrived, have they?
I'm sure about the first tag question, but not about the second one.
Is the tag OK? If I write "hasn't they" it doesn't make any sense to me.
I'll appreciate if somebody could help me solving this doubt.
Best Answer
The first one should be:
And the second is right:
You are changing the number of the pronoun, 'somebody' is 1 person, but by the end of the sentence you are talking about 'they' which is more than one person, so the use of (is) must change to (are).
The same goes for the second sentence, has -> have
Note: 'Nobody has' probably counts as a negative verb, so I use 'have' instead of 'haven't'.