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

SOLUTION: contract

PROBLEM: Sentence1: evaporation can be used for separating a solute from a solvent in a solution. 
Sentence2: Evaporation can be used for segregation a solute from a solvent in a solution.

SOLUTION: a

PROBLEM: Sentence1: Plants are the primary producers on earth. 
Sentence2: Bacteria in the soil convert nitrogen into a form usable by producers.

SOLUTION:
producers