instruction:
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.
question:
Sentence1: Nonmetal elements are far fewer in number. 
Sentence2: There are 17 nonmetals on the periodic table.
answer:
Nonmetal


question:
Sentence1: Echinoderms lack respiratory and excretory systems. 
Sentence2: echinoids lack a respiratory system.
answer:
respiratory


question:
Sentence1: fog is formed by water vapor condensing in the air. 
Sentence2: When air cools, the water vapor in the air condenses.".
answer:

condensing