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: sharpening an object causes that object to change shape. 
Sentence2: sharpening a knife causes it to change shape.

A: causes
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Q: Sentence1: Most copepods feed on phytoplankton. 
Sentence2: most copepods feed on bacteria and algae that use sunlight to make food.

A: copepods
****
Q: Sentence1: Bone is less flexible than cartilage but stronger. 
Sentence2: Cartilage is made up of chondrocytes, and a matrix, or ground substance.

A:
cartilage
****