Question

The books lay all together in a heap. NPCR2 263

Accepted Answer

书都堆在一起。在  is often used as a result of an action to indicate that somebody/something is located somewhere with noun/noun phrase indicating place as object

Front	The books lay all together in a heap.
Back	书都堆在一起。在 is often used as a result of an action to indicate that somebody/something is located somewhere with noun/noun phrase indicating place as object
Page	NPCR2 263

Books Lay Heap 书都堆在一起 在 Is Result Action

Books Lay Heap 书都堆在一起在 Is Result Action