The Two Doors

Question: There are two doors ten feet apart: One door leads to Heaven, and one door leads to Hell. In between both doors are two guards; one who always tells the truth, and another who always lies. Only these two guards know which door leads to Heaven, and which to Hell. What question can you ask both guards to find out which door leads to Heaven?

Question: What do you get when you cross a witch with sand?

Question: What do you call a sad bird?

Question: What tastes better than it smells?

Question: What goes in the water black and comes out red?

Question: What loses its head in the morning and gets it back at night?