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: an earthquake causes the ground to shake. 
Sentence2: A number of buildings in Istanbul also were damaged in the earthquake.

A: earthquake
****
Q: Sentence1: Combustion generates toxic fumes. 
Sentence2: High temperatures can cause toxic fumes.

A: fumes
****
Q: Sentence1: some light bulbs convert electricity into light and heat energy. 
Sentence2: Kinetic energy is energy of movement and also includes heat energy and light energy.

A:
heat
****