Answer:
The last man on Earth received a phone call, who was the caller?
I am black when you buy me red when you use me when I turn white you know itβs time to throw me away.
What goes up and down, but does not move?
I can be swallowed But I can also swallow you.
People walk in and out of me. They push me and I follow. When they walk out on me I close up and I stay waiting for the next person to walk into my life when I have a more open mind
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?