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

A: Bound
****
Q: Sentence1: bacteria cause food to spoil. 
Sentence2: Food poisoning occurs when spoiled food is eaten.

A: spoil
****
Q: Sentence1: All birds are placed in the Class Aves. 
Sentence2: Organisms in the class Aves have beaks that are generally adapted for the food they eat.

A:
Aves
****