a pile of piles of
后面可加可数名词,也可以不可数名词
a pile of 一堆；很多
例句
His body was tossed on a pile of corpses and his remains have never been recovered
Luda had found it next to a pile of garbage about six blocks from her home
piles of
成堆的；一大团；一大批
例句
When the Americans marched in,they discovered huge piles of dead bodies and starving survivors.
Standing over his new laundry area,he surveyed the surrounding piles of wood and wreckage.