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: Smoking accelerates the aging process. 
Sentence2: smoking accelerates the death of cells.
[A]: Smoking


[Q]: Sentence1: an animal usually requires a warm body temperature for survival. 
Sentence2: Warm blooded animals have a constant body temperature.
[A]: animal


[Q]: Sentence1: if humans disturb animals in a location then those animals will move to a different location. 
Sentence2: Whales will move to a new location  due to whale watching boats.
[A]:
location