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: Very often their only metal object in the house is a cooking pot or a knife. 
Sentence2: sharpening a knife causes it to change shape.

SOLUTION: knife

PROBLEM: Sentence1: if soil is permeable then water easily flows through that soil. 
Sentence2: if soil is permeable then h2o easily flows through the soil.

SOLUTION: flows

PROBLEM: Sentence1: Lung cancer is most often caused by exposure to tobacco smoke. 
Sentence2: tobacco smoke is very deadly.

SOLUTION:
smoke