Answer:
Once you know it exists, it no longer exists. What is it?
I am a king but also a common device of measure. What am I?
What starts with the letter T, is filled with T and ends in T?
Before Mt. Everest was discovered as the highest mountain in the world, which mountain was the highest?
What can you never get rid of when you lose it?
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?