A．Because there are still many things people cannot explain.
B．Because people know little about the birth and death of human beings.
C．Because people want to control the weather and many other situations.
D．Because superstitions can help them realize what they wish to do.

A．When they used salt to melt snow.
B．When they started to preserve food with salt.
C．After they found animals licking salt.
D．After they found salt's magical powers.