TASK DEFINITION: In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant.
PROBLEM: Solution caves are formed in limestone and similar rocks by the action of water. After a rain, water seeps into cracks and pores of soil and rock. The water percolates beneath the land surface. Some of the water reaches a zone where all the cracks and pores in the rock are already filled with water. Rainwater absorbs some carbon dioxide as it passes through the atmosphere and even more as it drains through soil and decaying vegetation. The water combines chemically with the carbon dioxide. A weak carbonic acid solution is formed. This acid slowly dissolves calcite, forms solution cavities, and excavates passageways.

SOLUTION: Solution caves ,carbon dioxide ,weak carbonic acid solution ,calcite ,solution cavities

PROBLEM: Fluid. Waste enters the kidneys. A processing moment in the kidneys let waste and fluid pass. Prevents larger molecules to pass. Fluid goes back to the bloodstream. Bad waste is removed. The final product is turned into urine.

SOLUTION: fluid ,waste;larger molecules;bad waste ,urine

PROBLEM: The moon orbits the earth. The earth orbits the sun. The moon comes between the sun and the earth. The sun is totally blocked. A solar eclipse is occurring.

SOLUTION:
earth ,moon ,sun ,solar eclipse