An dtugann gach lá rud éigin nua?
Does every day bring something new?
An bhfuil aon dá lá mar a chéile?
Are any two days the same?
Ní mar a chéile aon dá lá.
No two days are alike.
Grammar of the Main Sentence:
ní + mar a chéile + aon dá lá
Negation (ní) + Comparison Phrase (mar a chéile) + Subject (aon dá lá)