(2) A. What it means is that the stone is exposed after the water falls, and no new substance is generated, which is a physical change; B, tempering into steel is to remove excess carbon from pig iron through chemical changes, which belongs to chemical changes; C. Obtaining gold from ore and producing new substances is a chemical change; D. Dropping water into ice means that water changes from liquid to solid, but the state has changed, which is a physical change; E. Dropping through a stone is a physical change in which the stone is washed out of the hole by dripping for a long time, and no new substance is generated; What F does is a change in shape, and no new substance is produced. This is a physical change.
So, the answer is: (1) gold; Water; Molecules are constantly moving; (2) BC.