饼干放久了会碎成小块。

The cookies will ___crumble into small pieces if left out too long.

由于缺乏维护，这座古老的城墙开始慢慢崩塌。

The ancient city wall began to ___crumble due to lack of maintenance.

晚餐后我们享用了覆盆子碎屑甜点。

We had a raspberry ___crumble for dessert after dinner.