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: Leeches are external parasites. 
Sentence2: Leeches live on the surface of their hosts.
[EX A]: Leeches

[EX Q]: Sentence1: Plants are grown in greenhouses and protected from wild butterflies. 
Sentence2: Plants are grown where they are protected from the cold.
[EX A]:
Plants