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: Hydrogen bonds cause water to expand when it freezes. 
Sentence2: Hydrogen bonds Hydrogen bonds are primarily electrostatic in origin.
[A]: Hydrogen


[Q]: Sentence1: Ribosomes are small organelles where proteins are made. 
Sentence2: Ribosomes are assembled inside the nucleus.
[A]: Ribosomes


[Q]: Sentence1: Wound healing Wound healing is a critical aspect of surgery. 
Sentence2: zinc can have a positive impact on surgery.
[A]:
surgery