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


[Q]: Sentence1: Lancelet larvae are free-swimming. 
Sentence2: some larvae lack a hardened backbone.
[A]: larvae


[Q]: Sentence1: Evaporation of sweat uses energy, and the energy comes from body heat. 
Sentence2: Evaporation of sweat uses kinetic energy from the body.
[A]:
Evaporation