In the entry for 'cosúil', does FGB give:

Cé leis is cosúil í? Cé leis a bhfuil sí cosúil? Whom is she like?

If so, why isn't it ar cosúil ( indirect relative) in the copula version?

Thanks.

I'm sorry but i don't understand why it would be "ar" at all? Can you expand a little?

There are some constructions that "irregularly" use the direct relative, usually for historical reasons. I'd
suspect this is one of them, but perhaps I'm wrong. Conamara Irish is the most conservative with using
the relatives, so these type of irregular constructions are less common in it.

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The dialect I use is Cork Irish.
Ar sgáth a chéile a mhairid na daoine, lag agus láidir, uasal is íseal

If it hadn't been in FGB, I would have thought the 1st one was wrong. It doesn't follow the normal rules.
I would have said "Cé leis ar cosúil í?" is using the copula (cé leis is always followed by the indirect relative), but I think most people say Cé leis a bhfuil sí cosúil?" or "Cé a bhfuil sí cosúil leis?".

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Is fearr Gaeilg na Gaeltaċta ná Gaeilg ar biṫ eile
Agus is í Gaeilg Ġaoṫ Doḃair is binne

An-cheist! Mar a dúirt Lughaidh, murach gur FGB atá i gceist, bheinn an-amhrasach faoi.

Néal níor chodail mé ar mo leaba dhom aréir agus mé ag machnamh air.

Má thagann tú ar mhíniú, cuir ar an eolas muid, ldt.