A man who lived on the top floor of a twenty story building had to go up and down daily for work, and of course, for food and the other necessities. On most days he could only ride the elevator to the fifteenth story, and he would have to walk the rest of the way. When it rained, however, he could ride all the way up to the twentieth story. Why?

If your uncle’s sister is not your aunt, what relation is she to you?

Mr. John lives in a mansion. He is very rich. He is so rich that he has a maid, a cook, a butler, and a lifeguard. Yesterday, Mr. John was found dead. The chief detective was coming from Sunday church to investigate. The police were already there. They caught six suspects. The maid, the butler, the cook, the lifeguard, the postman, and Mrs. John. The maid said she was dusting. The butler said he was playing a board game with Mr. John’s sons. The cook said he was making dinner. The lifeguard said he was watching Mr. John’s daughter swim in the pool. The postman said he was delivering mail. Mrs. John said she was watching TV. Who is lying?

Open it, and you can not see it without a mirror.
Close it and you can not see it at all.
What is it ?