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: moss causes chemical weathering. 
Sentence2: If the moss was completely dried then it is dead.

A: moss
****
Q: Sentence1: high mountains with well-rounded peaks can be formed by collision of crustal plates. 
Sentence2: high mountains with well-rounded peaks can be formed by collision of plate tectonics.

A: collision
****
Q: Sentence1: thick fur can be used for keeping warm. 
Sentence2: foxes warm up with fur.

A:
fur
****