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 switch is used to start the flow of current in an electrical circuit. 
Sentence2: lights are on when there is flow of current in an electrical circuit.

SOLUTION: circuit

PROBLEM: Sentence1: Osteoporosis is a disease in which osteoclasts are more active than osteoblasts. 
Sentence2: a thinning and weakening of bone is a disease in which osteoclasts are more active than osteoblasts.

SOLUTION: active

PROBLEM: Sentence1: Arthropods have a life cycle with sexual reproduction. 
Sentence2: scorpions have a low rate of reproduction.

SOLUTION:
reproduction