Riddle #78

What man cannot live inside a house?

Each morning I appear to lie at your feet. All day I will follow no matter how fast you run, yet I nearly perish in the midday sun.

What room do ghosts avoid?

I don't have eyes, but once I did see. Once I had thoughts, but now I'm white and empty.

What can run but can't walk?

Two girls ate dinner together. They both ordered iced tea. One girl drank them very fast and had finished five in the time it took the other to drink just one. The girl who drank one died while the other survived. All of the drinks were poisoned. How is that possible?

Poor people have it. Rich people need it. If you eat it you die. What is it?

I am alive without breath and cold as death. I am never thirsty but always drinking. What am I?

I always come down and never ever go up? Think, think and think! We all just love it.

Why is a river rich?

Using only and all the numbers 3, 3, 7, 7, along with the arithmetic operations +,-,*, and /, can you come up with a calculation that gives the number 24? No decimal points allowed. [For example, to get the number 14, we could do 3 * (7 - (7 / 3))]