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.

Q: Sentence1: Acids dissolve in base and turn blue litmus red. 
Sentence2: acid changes color.

A: Acids
****
Q: Sentence1: Excretion is the process of removing wastes and excess water from the body. 
Sentence2: parasites remove waste from their bodies.

A: wastes
****
Q: Sentence1: Cells are programmed to divide only a set number of times. 
Sentence2: Division can only happen a certain number of times before apoptosis kicks in.

A:
divide
****