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: the mass of a planet causes the pull of gravity on that planet. 
Sentence2: the mass of a planet is what causes things to have weight.
[EX A]: mass

[EX Q]: Sentence1: Bacteria and Viruses Bacteria and viruses can cause diseases. 
Sentence2: bacteria can have a negative impact on an organism.
[EX A]: Bacteria

[EX Q]: Sentence1: hiding can be used for avoiding predators. 
Sentence2: Hiding can be used for avoiding carnivores or omnivores.
[EX A]:
avoiding