Sentence:This painting depicts a swooping falcon with its claws bared pursuing a [e1]host[/e1] of nine [e2]sparrows[/e2] in frightened flight, the two forming an energetic arc enriched by the lifted right wing of the falcon and the panicked sparrows dispersed in all directions.
 e1: host. 
 e2 : sparrows.
Answer: Member-Collection(e2,e1)