instruction:
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.
question:
Sentence1: forming coal requires decaying vegetation. 
Sentence2: Forming fossil fuels requires decaying vegetation.
answer:
decaying


question:
Sentence1: Acid rain is precipitation which pH is 5.7 or lower. 
Sentence2: gases from burning coal causes precipitation which pH is 5.7 or lower.
answer:
5


question:
Sentence1: Behaviors can be learned through play. 
Sentence2: Behaviors can be learned through games.
answer:

Behaviors