Good Riddles

Question: I can pogo on the moon, but not Mars. I can pogo on this table, but not on a stick. What can assure us to be able to pogo on objects at all times?

Question: There are two women on a stage. One is in tears, the other is smiling. Who are these women (not names), why are they expressing that facial expression, & what kind of situation are they in? HINTS: These women don't work as employees on setting up the stage. This is not a comedy show. The stage has curtains, and this show is very famous. The person with tears is in fact overwhelmed with joy, and the other is "sad." The crowd laughs and cheers at the joyful woman. These women are no older than 25 years old. Both women are wearing a very expensive dress. What's the answer?

Question: what comes up but never goes down

Question: What is in the middle of a human?

Question: I am a teacher, yet I am not a human nor a robot.