Which one is very usefull....?

Do you mean useful as in school subjects or useful to Human Beings as a whole?

I use to manage depression, listening musiq, playing violen and i like chocolates, and i feel i get refreshed after having my chocolates. And best remedy is Meditation, try breathing exercise, it will help you balance and handle depression.

Of course they are all very useful, but the one I like most, so would consider most useful is science. I keep studying it, and have found it actually supports intelligent design way more than evolution, which really has basicly almost no support! [Most people don't realize that however.] Math! yikes.. if i can't figure it on a calculator.. it's a chore. I can't even remember all my multiplication table anymore! I should say english is most useful as I do love to write, and knowing the correct way to do so comes in handy.. :))