Answer:
You draw a line. Without touching it, how do you make the line longer?
What can I not be tomorrow?
There are two sisters: one gives birth to the other and she, in turn, gives birth to the first. Who are the two sisters?
What was the longest river in the world before the Amazon River was discovered?
What is yours but only used by others?
I only exist when you are here. Where you never were I can never be.