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: If the skin is painful, seek medical attention. 
Sentence2: If your skin hurts, your touch receptors will sense differences.
[A]: skin


[Q]: Sentence1: the moon revolving around the Earth causes the phases of the moon. 
Sentence2: Lets start our discussion of the Moon's phases with the New Moon phase.
[A]: phases


[Q]: Sentence1: Complex chemistry is needed to carry out all the functions of life. 
Sentence2: Complex chemistry is needed to promote quality of life.
[A]:
Complex