drop/fall/sink like a stone idiom
快速直线下落；象石头一样落下
to move very quickly down in a straight line
Witnesses say that there was an explosion and then the plane dropped like a stone. 目击证说听到一声爆炸，然后飞机象石头一样坠落地面。
The ring fell into the water and sank like a stone. 那个戒指落到水里，象石头一样沉了下去。