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 Q]: Sentence1: folding an object causes that object to change shape. 
Sentence2: Folding an object causes that object to transform.
[EX A]: causes

[EX Q]: Sentence1: propulsion is used for flying by a spacecraft. 
Sentence2: When Apollo 12 took off, the spacecraft was hit by lightning.
[EX A]: spacecraft

[EX Q]: Sentence1: Ribosomes are sites where proteins are made. 
Sentence2: Ribosomes are assembled inside the nucleus.
[EX A]:
Ribosomes