Nazo nazo (riddles)

Just so I don't leave you too bored during my absence, here are a few riddles for you. In Japanese, they're called nazo nazo. One of our teachers wrote them on the blackboard for us last Monday. We were already given some of the answers but there's one that nobody has figured out yet and it's annoying me. I like riddles and I like thinking about the answers for a short amount of time but after a while, if I haven't figured it out, I just need to know the answer or I go crazy. It stays on my mind until someone tells me the answer.

Here is the one nobody has figured out yet: (our teacher is going to give us the answer next Monday but maybe you can guess the answer before : P ). Here is my best translation of it in English:

1) The person who makes it doesn't teach it. The person who has it doesn't know it. And the person who knows it doesn't want it. What is it?

Now here are a few others to which I already know the answer.

2) Everyone is born with one, and even though it's ours, everyone else uses it.


3) Even though you cut it over and over again, you can never cut it.


4) The longer we live, the bigger it gets, but it's something we don't want.


5) The person who makes it doesn't want it. The person who buys it doesn't use it. And the person who uses it doesn't see it. What is it?


Enjoy! See below for answers. Answers are written in white so just highlight the answer with your cursor.

1) Still unknown for now...
2) a name
3) water
4) age
5) a coffin