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: Bound and free ribosomes are structurally identical and interchangeable. 
Sentence2: Bound and free structures are in the cytoplasm where proteins are made.
[EX A]: Bound

[EX Q]: Sentence1: Light source is an ultra-bright, unbreakable LED Bulb. 
Sentence2: LEDs convert electricity into light and heat energy.
[EX A]: LED

[EX Q]: Sentence1: lack of moisture in the air causes low amounts of rainfall. 
Sentence2: Lack of humidity causes low rainfall.
[EX A]:
lack