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: erosion causes a river to become deeper and wider. 
Sentence2: On the contrary, the NILE is the longest river in Africa.

SOLUTION: river

PROBLEM: Sentence1: Echinoderms use pheromones to communicate with each other. 
Sentence2: Echinoderms are known for their round symmetry.

SOLUTION: Echinoderms

PROBLEM: Sentence1: cables are used for support by suspension bridges. 
Sentence2: metal, stainless steel and plastic are used to support suspension bridges.

SOLUTION:
bridges