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.

Sentence1: Some trees are maples. 
Sentence2: planting maples has a positive impact on an ecosystem.
maples

Sentence1: if an object is made of a material then that object has the properties of that material. 
Sentence2: items properties are the same as the materials the item is made of.
made

Sentence1: temperature changing can cause phase changes. 
Sentence2: Temperature changing can cause water to change to ice.

changing