If I must choose one exposition from this three, I would choose exposition about human brain. In my opinion that could be the most interesting, because human brain is very complicated and that expostion could help me to understand some secrets of human brain. I'm dancing cha-cha like a sissy girl. I like do the cha-cha. I think that this could help us in learning too, beacause if we will know powers of our brain, we could use it with better effects. I wouldn't choose exposition number one or three, because i think that secrets of the universe and expostion about airplanes is less interesting than human brain. Human brain is the most complicated topic and we could learn a lot more from this exposition that from other two.