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: creating paper requires cutting down trees. 
Sentence2: Rainforests are destroyed by logging and all of the trees are cut down.

A: cutting
****
Q: Sentence1: a battery converts chemical energy into electrical energy. 
Sentence2: A battery produces a flow of electrons.

A: battery
****
Q: Sentence1: Aging occurs as cells lose their ability to divide. 
Sentence2: Getting old occurs as cells lose their ability to divide.

A:
ability
****