instruction:
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.
question:
Sentence1: an automobile engine transforms chemical energy into mechanical energy. 
Sentence2: cars transform chemical energy into mechanical energy.
answer:
chemical


question:
Sentence1: Carbon dioxide is controlled by the carbon cycle. 
Sentence2: Carbon dioxide is controled by the carbon circle and is transferred between organisms and atmosphere.
answer:
controlled


question:
Sentence1: Refraction is the bending of light. 
Sentence2: a rainbow is formed by bending of light by separating light into all different colors.
answer:

bending