Good Riddles

Question: What is it you like to kill, but actually kills you?

Question: I dig out tiny caves, and store gold and silver in them. I also build bridges of silver and make crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs my help, yet many people are afraid to let me help them. Who am I?

Question: What do you have that I use more than you do?

Question: I am first in earth A second in heaven I appear twice in a week But you can only see me once in a year You can also see me in the middle of the sea What am I?

Question: If there were ten fish in an enclosed tank, and four swam away, three died, and three drowned, how many fish would be left?