(1) Rock 石头（的统称）
The geologist likes to collect rocks from all around the world.
地质学家喜欢在全世界到处收集石头。
(2) Stone（通常是比较大的）石头
The little boy got in trouble for climbing onto the large stone at the base of the monument.
小男孩爬不上去纪念碑底座上的那块大石头。
(3) Pebble 小石头；鹅卵石
Instead of sand, this beach has a shoreline made up of small gray pebbles.
岸边没有沙子，海岸线上布满了灰色的小石子。