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: Speciation events are thus examples of macroevolution. 
Sentence2: Speciation events occur over geologic time above the level of the species.

SOLUTION: Speciation

PROBLEM: Sentence1: For instance, glucose is a sugar. 
Sentence2: insulin helps cells take up sugar from the blood.

SOLUTION: sugar

PROBLEM: Sentence1: Cynodonts became more mammal-like as they continued to evolve. 
Sentence2: therapsids became more mammal-like as they evolved.

SOLUTION:
became