要,因为HOW MANY 后一定是接名词的复数.如果回答只有一个就不要加ES,如
I can see a box there .
加油!不明白再问!假如回答只是一个，也要加吗不用，即I can see a box there .那问句呢是how many boxes can you see? only one boxes还是how many box can you see？only one boxes是how many boxes can you see? only one box .