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.

Sentence1: All frogs are amphibians. 
Sentence2: frogs have permeable skin that easily absorbs substances from the environment.
frogs

Sentence1: Most genes contain the instructions for a single protein. 
Sentence2: Most genes contain the instructions for protein destinations.
Most

Sentence1: Water and the Nile River are important to Egypt. 
Sentence2: Erosion causes the Nile to become deeper and wider.

Nile