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.

Ex Input:
Sentence1: if a habitat can no longer support animals then those animals will move to another area. 
Sentence2: Each species of animal is unique.

Ex Output:
animals


Ex Input:
Sentence1: Protein Protein is needed for tissue maintenance and repair. 
Sentence2: protein repairs cells.

Ex Output:
Protein


Ex Input:
Sentence1: an electron microscope is used for seeing very small objects by making them appear bigger. 
Sentence2: Electron microscopes can make cells appear larger.

Ex Output:

appear