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: skin is used for protecting the body from harmful substances. 
Sentence2: Acids are harmful to tissue.
[A]: harmful


[Q]: Sentence1: Habitat destruction is the primary cause of extinction or threat of extinction for all animals. 
Sentence2: building housing developments may cause extinction.
[A]: extinction


[Q]: Sentence1: Hurricanes grow strength from warm waters. 
Sentence2: Hurricanes are worse over warm water and weaker over land.
[A]:
warm