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: Propane can be either a liquid or a gas. 
Sentence2: heat can be added to propane to change it's properties through the boiling process.

A: Propane
****
Q: Sentence1: Ejaculation allows males to reproduce. 
Sentence2: propelling sperm from the epididymes allows males to reproduce.

A: allows
****
Q: Sentence1: Precipitation increases moisture. 
Sentence2: Moisture conditions range from damp to dry.

A:
moisture
****