I’m tall when I’m young, and I’m short when I’m old. What am I?

I am the fastest animal but cannot climb the tree. What am I?

I know there are two methods by using three time the same number with a plus(+) operator , you can make sum as 60.

One of them is 20+20+20.

whats the other way ?

This is a most unusual paragraph. How quickly can you find out what is so unusual about it? It looks so ordinary, you'd think nothing was wrong with it. Actually, nothing IS wrong with it. But it is not as ordinary as you might think. If you think about it for a bit, you will find out why it is truly so unusual. So what is it? What is so unordinary about this paragraph?

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?

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

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

How many sides does a circle have?

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?