TASK DEFINITION: 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.
PROBLEM: 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.

SOLUTION: made

PROBLEM: Sentence1: creating wood-free paper does not require cutting down trees. 
Sentence2: creating printed media requires cutting down trees.

SOLUTION: creating

PROBLEM: Sentence1: a warm front causes cloudy and rainy weather. 
Sentence2: If warm air is advancing on cold air, the front is designated a warm front.

SOLUTION:
front