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.

Ex Input:
Sentence1: friction causes the temperature of an object to increase.
Sentence2: internal combustion engines get hot.

Ex Output:
temperature

Ex Input:
Sentence1: creating paper requires cutting down trees.
Sentence2: Rainforests are destroyed by logging and all of the trees are cut down.

Ex Output:
cutting

Ex Input:
Sentence1: high pressure systems cause clear weather.
Sentence2: During windy weather, the pollution is dispersed and cleared away.

Ex Output:
clear