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: smell is used for finding food by some animals. 
Sentence2: Food includes small rodents and birds.

SOLUTION: food

PROBLEM: Sentence1: Muscles can only contract. 
Sentence2: Contraction is a type of movement.

SOLUTION: contract

PROBLEM: Sentence1: a circle graph can be used to display percents. 
Sentence2: A circle graph can be used to display data values.

SOLUTION:
a