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: Leeches are external parasites. 
Sentence2: Leeches live on the surface of their hosts.
[A]: Leeches


[Q]: Sentence1: Information on DNA is organized into genes. 
Sentence2: DNA codes for proteins.
[A]: DNA


[Q]: Sentence1: a light bulb requires electrical energy to produce light. 
Sentence2: coal can power a light bulb.
[A]:
light