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: cell division often causes growth. 
Sentence2: Cell division leads to reproduction.

Answer: cell


Question: Sentence1: boiling means change from a liquid into a gas by adding heat energy. 
Sentence2: boiling changes a liquid into steam.

Answer: liquid


Question: Sentence1: a pulley is used for lifting objects. 
Sentence2: A pulley is used for lifting mass.

Answer:
a