What am I?

*Forward* *backwards* is what I do all day. I come in all different shapes and sizes. I can be scary, and I can calm you down. What am I?

I'm so fast you can't see me, though everyone else can see straight through me. I don't stop until the day you die. What am I?

i am something i go up but never come down what am i

I have a straight back and sharp teeth to cut objects. What am I?

Riddles and Answers