Good Riddles

Question: A person has one lion, one lamb and a bundle of grass. He wants to cross a river but there is only one boat and it can't sustain the weight of more than two articles at time. Also, he has to make sure that the lion doesn't eat the lamb and the lamb doesn't eat the grass. How will he get to the other side of the river with all three intact?

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 fill up a bathtub with water and you have a teaspoon, tablespoon, and fourth cup. What is the fastest way to empty the bathtub?

Question: I used to fill rooms but now I'm a tower,
I can stay put or I can travel far.

What am I?

Question: You are a prisoner. The only way to escape the prison is to walk down a very long hallway that takes 2 hours to get through. Guards come out of a door halfway down the hall every hour and take any prisoners walking out back to the prison and escort any visitors out of the prison. The guards cannot tell the difference between prisoners and visitors.

How do you escape?