Sentence:It is fearful to meet in a narrow defile, or where the road winds around the edge of a precipice, a [e1]drove[/e1] of reckless [e2]donkeys[/e2] and mules descending the mountain, urged on by the cries and lashes of the muleteers behind.
 e1: drove. 
 e2 : donkeys.
Answer: Member-Collection(e2,e1)