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: riding a bike does not cause pollution. 
Sentence2: riding a bike does not release particles.
[EX A]: bike

[EX Q]: Sentence1: a flashlight converts chemical energy into light energy. 
Sentence2: Chemical energy converted to light energy requires batteries.
[EX A]: chemical

[EX Q]: Sentence1: Bile exits gallbladder by common bile duct. 
Sentence2: the gallbladder reduces the acidity of food entering from the highly acidic stomach.
[EX A]:
gallbladder