Cá bhfuil Brian -- Where is Brian

Let me introduce two forms of the verb Tá to you:
neamhspleách (independent) and spleách (dependent)
Tá is the foirm neamhspleách (independent form)
used when no verbal particles such as ní or cá come before the verb.
An bhfuil is the foirm spleách which we have already met in a previous lesson.
Now we see the mír cheisteach interrogative particle cá being followed by
an fhoirm spleách: Cá bhfuil Brian -- Where is Brian
An fhoirm spleách appears also in the word níl the negative of tá
but most of it is elided or hidden: níl is really ní fhuil.

Click on Tá, Níl, and An bhfuil to see the previous discussion of this verb.