swim的过去式是：swam。swim的基本意思是“游泳”“游过”，指靠摆动身体在水中前进或漂浮。swim还可作“漂浮”、“飘忽”、“滑行”解，引申可表示“旋转，摇晃，眩晕”。

swim的过去式例句：

1、I was pitched into the water and swam ashore.

我被甩到水里后向岸边游去。

2、The goldfish swam round and round in their tiny bowls.

金鱼在小小的鱼缸里一圈圈地游来游去。