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.

[EX Q]: Sentence1: chemical splashing can cause harm to humans. 
Sentence2: chemical splashing can cause harm to animals.
[EX A]: cause

[EX Q]: Sentence1: a fire requires oxygen to burn. 
Sentence2: Oxygen has  eight protons and eight electrons.
[EX A]: oxygen

[EX Q]: Sentence1: lakes are formed by precipitation and runoff. 
Sentence2: lakes are formed by rain and runoff.
[EX A]:
and