TASK DEFINITION: Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.
PROBLEM: Sentence1: Cnidarians are invertebrates such as jellyfish and corals. 
Sentence2: Jellyfish and corals are radial, tentacled animals that live mostly in the seas.

SOLUTION: corals

PROBLEM: Sentence1: Macroevolution occurs over geologic time above the level of the species. 
Sentence2: adding new genes with special capability occurs over geologic time above the level of the species.

SOLUTION: above

PROBLEM: Sentence1: a refrigerator is used for keeping food fresh for a long period of time. 
Sentence2: To prevent bacterial food poisoning, the basic rule is to keep hot foods hot and cold foods cold.

SOLUTION:
food