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 solution is formed by one substance being dissolved in another substance. 
Sentence2: A solution is formed when limestone is dissolved in ocean water.

SOLUTION: formed

PROBLEM: Sentence1: a camera is used for recording images. 
Sentence2: a camera is used for recording binary.

SOLUTION: camera

PROBLEM: Sentence1: Macroevolution occurs over geologic time above the level of the species. 
Sentence2: adding new genes with special capability occurs over geologic time above the level of the species.

SOLUTION:
above