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: Capillaries are microscopic vessels. 
Sentence2: Lymph is a fluid that leaks out of microscopic vessels into spaces between cells.

SOLUTION: microscopic

PROBLEM: Sentence1: Stress is the applied force, strain is the change in shape. 
Sentence2: Paper is crumbled when stress and strain is applied in order to change the shape.

SOLUTION: Stress

PROBLEM: Sentence1: a flashlight requires a source of electricity to produce light. 
Sentence2: Electric power sources are ordinary batteries.

SOLUTION:
electricity