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.

[EX Q]: Sentence1: Propane can be either a liquid or a gas. 
Sentence2: heat can be added to propane to change it's properties through the boiling process.
[EX A]: Propane

[EX Q]: Sentence1: Weather today is said to be sunny and clear. 
Sentence2: High pressure systems cause it to be sunny.
[EX A]: sunny

[EX Q]: Sentence1: chlorophyll is used for absorbing light energy by plants. 
Sentence2: Chlorophyll is the plant's oxygen producer.
[EX A]:
chlorophyll