The apple falls down on the ground.改为现在进行时.

The apple falls down on the ground.改为现在进行时.
The apple falls down on the ground.改为现在进行时.

The apple falls down on the ground.改为现在进行时.
应该是：
The apple is fallig down on the ground?
这个苹果正落到地上.

The apple is falling down on the ground.