TASK DEFINITION: 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.
PROBLEM: Sentence1: Heat production is increased by shivering and non-shivering thermogenesis . 
Sentence2: Heat production occurs when many muscles contract a little bit all at once.

SOLUTION: Heat

PROBLEM: Sentence1: Some pelycosaurs gave rise to a group of animals called therapsids. 
Sentence2: Like most other groups of synapsids, all pelycosaurs are now extinct.

SOLUTION: pelycosaurs

PROBLEM: Sentence1: Loss of ozone has created an ozone hole over Antarctica. 
Sentence2: Ozone is triatomic oxygen, O3.

SOLUTION:
ozone