A scent or smell. A scent is important to both humans and animals and both search for scents (for different reasons). A scent travels through the air to benefit humans and animals, again, for different reasons.
Special thanks to Vavessa for the answer to this one.
There are two tricks to this one. The first is 1 × 0. But it’s mostly there as a distraction. Yes, 1 × 0 is 0, but that doesn’t affect anything else in the equation. The second, far trickier element is that the lines ending with 1 don’t have a + sign next to them. That means they should be combined with the following line.
They are the only letters in the alphabet that are not found at the beginning of the name of a state in the United States of America. The rest of the letters in the alphabet, namely ACDFGHIKLMNOPRSTUVW, start the name of at least one state. Incidentally, eight different states each start with the letters M and N, tying them for the most states starting with a particular letter. The next highest is a three-way tie between A, I and W with four each.
A windmill. The typical windmill, like the ones Don Quixote chased, have four vanes or sails. You might even say they look like wings. Windmills don’t have emotions, so they can’t laugh or cry. And since they don’t have actual wings, windmills don’t get off the ground. A well-oiled little bugger won’t make a peep.