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: Heterotrophs are living things that cannot make their own food. 
Sentence2: food contains organic molecules.
[A]: food


[Q]: Sentence1: boiling means change from a liquid into a gas by adding heat energy. 
Sentence2: boiling changes a liquid into steam.
[A]: liquid


[Q]: Sentence1: Each human body is unique. 
Sentence2: disease-causing microbes have a negative impact on humans.
[A]:
human