Throughout history, people have used many methods to clean their teeth. Some ancient people chewed on frayed twigs. Others rubbed their teeth with cloth or swabbed them in vinegar. The Egyptians may have been the first people to use toothpaste when they mixed powdered pumice (a porous rock formed in volcanic eruptions) with vinegar and applied it to their teeth in the 100's B.C. Some toothpastes still contain pumice, but science has since supplied other toothpaste ingredients that the ancient Egyptians never dreamed existed.
I have heard that carbon monoxide is extremely poisonous. Can you explain why?
That's quite a snazzy outfit you have on, but an invisibility cloak would totally complete the look. But which one will you choose from the wardrobe of invisibility? We better test your knowledge on the subject of invisibility in fiction and myth.