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: microscope is used to see small things by biologists by making them appear bigger. 
Sentence2: Something invented by Leeuwenhoek is used to see small things by biologists by making them appear bigger.
appear

Sentence1: Lions live in social groups called prides. 
Sentence2: Chimpanzees live in social groups called communities.
groups

Sentence1: cycles of freezing and thawing water cause ice wedging. 
Sentence2: cycles of freezing and thawing water are common in high, cold latitudes,  can force soil particles together.

cycles