Good Riddles

Question: The more you take, the more you leave behind.
What are they?

Question: There are 4 light bulbs in a room and 4 switches corresponding to these four light bulbs (in a random order). You cannot see the light bulbs from where the switches are.

If you can only visit the room with the light bulbs once, how can you figure out which switch belongs to which light bulb?

Question: It brings light to a dark dark world,
In a current it travels and through tunnels it's hurled.
Touch it and it'll kill you.

What is it?

Question: You have two books. One of them is upside-down and the other is rotated so the top of the book is facing you.

What is the sum of the first page in each book?

Question: I have lakes with no fish.
I have roads with no cars.

What am I?