It goes up, but at the same time goes down. Up toward the sky, and down toward the ground. It's present tense and past tense too, come for a ride, just me and you. What is it?
NASA was considering sending canaries into space to study them under zero gravity. The project was scrapped when someone realized that in spite of having sufficient water supplies, they could die of dehydration within a few hours. Why?
Two sisters we are, one is dark and one is fair,
In twin towers dwelling we're quite the pair,
One from land and one from the sea,
Tell us truly, who are we?
Two sentries were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?" How did he know that his companion was smiling?
I have two arms, but fingers none. I have two feet, but cannot run. I carry well, but I have found I carry best with my feet OFF the ground. What am I?