very hard

Question: if last year "shoe" was written with a "s" how do we wright it today

Question: When you're given one, you'll have either two or none?

Question: During what month do people sleep the least?

Question: When is 99 more than 100?

Question: You have a glass of water that looks about half full. How can you tell, only using the glass of water itself, if the glass is half full or not?

The glass is a right cylinder.

Question: The more you add, the less it weighs.