Question

There ______ mountains of rubbish in the park in the last few days. A. have

Answer 1

There作为引导词，表示存在的＂有＂，后面必须是be动词，句中的时间状语 in the last few days （在最近的几天里）暗示了应该用现在完成时，there be的现在完成式是：There have been 。所以此句空白处应该填写have been。

Answer 2

has had；
in the last few days用于完成时态

Answer 3

had一般 过去式。