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: an image in a mirror is formed by reflecting light. 
Sentence2: mirrors can be seen with our eyes.
[A]: mirror


[Q]: Sentence1: Leaves make food for the plant. 
Sentence2: Some producers have leaves to help use energy and inorganic molecules.
[A]: Leaves


[Q]: Sentence1: global warming is when worldwide temperature increases. 
Sentence2: Global warming blamed on CO2.
[A]:
global