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: Water is essential for all life on Earth. 
Sentence2: H2O is needed for all life on Eartth.

A: Earth
****
Q: Sentence1: Here, the lungs supply the blood with oxygen. 
Sentence2: Brain cells die quickly if their blood supply is cut off.

A: blood
****
Q: Sentence1: the vanes rotating in an electric fan causes air to move. 
Sentence2: Many computer Cases cool down temperature by using Cooling Fan.

A:
fan
****