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: Mammals generate heat mainly by keeping their metabolic rate high. 
Sentence2: food keeps mammals' metabolic rates high.
[EX A]: Mammals

[EX Q]: Sentence1: Secondary accidents are a major problem under driving conditions of reduced visibility. 
Sentence2: Bad weather increases the risk of car accidents.
[EX A]: Secondary

[EX Q]: Sentence1: Most of the earth's water is liquid. 
Sentence2: Most people can survive only a few days without liquid.
[EX A]:
liquid