AT + indefinite article + noun
A search in the NOW corpus for: at_II _AT1 _NN 1 AT A TIME 475982 2 AT A PRESS 98426 3 AT A COST 80801 4 AT A MEETING 65340 5 AT A NEWS 61714 6 AT A PRICE 54148 7 AT AN EVENT 49461 8 AT A CAGR 44712 9 AT A RATE 41236 …