RiDDleS, a fun way to learn English

Hi, Guys!!!, 

Riddles can be an useful entertaining way to learn English. Some of these are easy, and even very similar to your language, but some others are difficult. Ready, steady, GO!!!

1. What is at the end of everything?
2. What starts with "t", ends with "t" and is full of "t"?
3. What starts with "e", ends with "e" but only has one letter?
4. What starts with "p", ends with "e" and has 10,000 letters? 
5. Brothers and sisters have I none, but that man's father is my father's son. Who is that man?
6. Take off my skin. I won't cry, but you will. What am I?
7. I run all day but I'm always at the same place. What am I?
8. What is as big as an elephant, but weighs nothing at all?
9. What has four legs but cannot walk?
10. What has to be broken before you can use it?    

ANSWERS:
1. The letter G.
2. A teapot.
3. An envelope.
4. The post office
5. My Son.
6. An onion.
7. A clock.
8. The shadow of an elephant.
9. A table.
10. An egg.