Can you solve this picture maths equation?

I go up and I go down.
I go up towards the beautiful sky and down toward the green ground.
I am present tense.
I am past tense too
Children love me.

Who Am I?

What breaks yet never falls, and what falls yet never breaks?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

A man calls his dog from the opposite side of a river. The dog crosses the river without a bridge or a boat and manages to not get wet. How is this possible?

If eleven plus two equals one, what does nine plus five equal?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

How many sides does a circle have?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?