sentence 1: How do I know if I'm good?
 sentence 2: How do I know what I'm good at? sentence 1: If water were a nonpolar molecule, how would the properties of water be different?
 sentence 2: Why is water considered to be a nonpolar molecule? sentence 1: Are there undiscovered elements on other planets?
 sentence 2: What are the chances that elements we don't know of exist on other planets or in other galaxies?
not same meaning
not same meaning
same meaning