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.

Q: Sentence1: Mammalian teeth are important for digestion. 
Sentence2: bats' teeth are important for digestion.

A: digestion
****
Q: Sentence1: Earthquakes cause massive damage. 
Sentence2: tectonic plates being pushed together causes massive damage.

A: damage
****
Q: Sentence1: Earthquake magnitude is a logarithmic measure of earthquake size. 
Sentence2: A seismograph is a logarithmic measure of earthquake magnitude.

A:
Earthquake
****