"Dream may be more important than sleep．We all need to dream．"Some scientists say．
Dreams take up about one quarter of our sleeping time．People have several dreams each night．Dreams are like short films．They are usually in color．Some dreams are like old films．They come to us over and over again，That may be because the dreamer is worrying about something．Dreaming may be a way of trying to find an answer．
Some people get new ideas about their work firom dreams．They may think about their work all day．These ideas can carry over into drams．
Sometimes we wake up with a good feeling from a dream．But often we can't remember the dream．Dreams can go away quickly from memory．
Too much dreaming can be harmful．The more we sleep，the longer we dream．The mind is hard at work when we dream．That is why we may have a long sleep and still wake up tired．

The main idea of the story is that（）.

A.what dream is
B.people like to sleep
C.dreams are live films
D.we always remember dreams