Good Riddles

Question: You have been poisoned by an evil scientist. He told you that the only antidote is the saliva of a gecko. He contains saliva of six different animals. A gecko, a lizard, a koala, a tapir, a giraffe, and a cow. He hasn’t labeled he test tubes containing the saliva f the animals. On the left is a table which four of the test tubes are one. On the right is a table which two of the test tubes are on. The lizards saliva is poisonous. The lizard and gecko test tubes are on the same table. The test tubes on the left are labelled 1, 2, 3, and 4. The gecko spit will not override the lizard poison. The lizard and gecko saliva are not right beside each other. You don't know where the cow test tube is. You know that the cow saliva is in 2 or 3 however. You know that the lizard test tube is not to the right of the cow. You only have time to drink two test tubes, which side do you run toward and which test tubes do you drink?

Question: I run over fields and woods all day. Under the bed at night I sit not alone. My tongue hangs out, up and to the rear, awaiting to be filled in the morning.

What am I?

Question: I am shorter when I stand and taller when I sit.
Sometimes I'm even called a pit.

What am I?

Question: Jack is taking a tour through a museum's American Presidents exhibit. The person leading the tour tells him "We have a picture of each presidency. Currently Barack Obama is the 43rd person to hold the office." But Jack quickly realizes that there are 44 pictures on the wall. But while walking through the exhibit he realizes why this is.

Why is there one too many photos?

Question: If a man carried my burden, he'd break his back.
I am not rich, but I always leave silver in my track.

What am I?