Good Riddles

Question: Spelled one way it mows the lawn spelled another you put it on

Question: I can be one, I can be two. I can be Open, Closed, Empty or Full. I can be Bare, but never a Bear. What AM I??

Question: When you close it, you see mysterious and funny looking images. But if you open it, the mysterious images are gone. What Am I?

Question: in all of written history I won't show up at the end of a sentence but I will be there in the end . . .

Question: A pond with dimension of 6m by 3m wil be filled of water lilies at exactly 30 days. Each day the number of water lilies will be doubled. First day 1, second day 2 etc... On what day it will fill half of the pond?