Good Riddles

Question: Tear one off and scratch my head. What once was red is black instead. What am I?

Question: Why was the mouse afraid of the water?

Question: Resurrected, they descend by the millions. Sometimes, to nourish and give life. Other times, to take lives or destroy. They have been known to fill entire valleys and block roads only to disappear before executing their long journey back to the top. What are they?

Question: People see through me, but none pass through without killing me. I can be anywhere, and can be seen double or single. What am I?

Question: A woman was born in 1818, she is 23 years old. How is this possible?