Answer:
When I live I cry if you don't kill me I'll die.
A trail, a union, together tied. Come across me and you will find you cannot change the course I'm on. Without me you cannot travel on. What am I?
What has a bottom at the top?
I am as hard as metal, yet as flimsy as glass. I shine like a star, yet I am only a rock. What am I?
I am pronounced as one letter, written with three. I come in blue, black, brown, or grey. Reverse me and I read the same either way. What am I?
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?