The water that falls from the sky today as rain may have once been part of the ocean. how can this be?

The water that falls from the sky today as rain may have once been part of the ocean because of the cycle of water.

Explanation:

The water cycles between the ocean, the land, and the atmosphere. In a simple way to explain:

1. Water from the ocean, streams, rivers, and lakes evaporates and go to the atmosphere.

2. In the atmosphere, the water cools and condense in clouds. 

3. Then, water from the clouds goes down to the land through snow or rain. 

4. Then, water from land is collected in ocean, streams, rivers, and lakes; and the cycle begins again. 

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands