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: lightning can cause a forest fire. 
Sentence2: Lightning can cause a natural cycle in forests.

SOLUTION: lightning

PROBLEM: Sentence1: if an animal sweats then that animal 's bodily water decreases. 
Sentence2: When an animal regulates their body temperature by releasing water, their bodily water decreases.

SOLUTION: bodily

PROBLEM: Sentence1: knowledge of the stars can be used to navigate. 
Sentence2: Of course, astronomers also study stars.

SOLUTION:
stars