pile up|piled up|piling up

我的工作堆积如山，所以我需要加班。

My work has ___piled ___up, so I need to work late.

我的工作开始在我的办公桌上堆积起来了。

My work is starting to ___pile ___up on my desk.

涨价之后，关于服务的投诉开始大量涌现。

Complaints about the service began to ___pile ___up after the price increase.

树叶正在院子里堆积起来，所以我们需要把它们耙干净。

The leaves are ___piling ___up in the yard, so we need to rake them.