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.
Input: Snow falls in an area for a very long time. The snow builds up for a very long time. The snow starts to become packed very firmly. The snow becomes something that's more like ice. Air pockets in the mass continue to grow smaller. The mass becomes solid and heavy enough to be called a glacier. The glacier moves because of gravity.
Output:
glacier ,snow ,mass