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: a camera is used for recording images. 
Sentence2: a camera is used for recording binary.

SOLUTION: camera

PROBLEM: Sentence1: Cancer is a disease in which cells divide out of control. 
Sentence2: Cancer is a disease in which cells grow and divide rapidly.

SOLUTION: Cancer

PROBLEM: Sentence1: mountains are formed by earthquakes. 
Sentence2: For big mountain background, check out the Himalayas .

SOLUTION:
mountains