I have an apple account and it's location is Singapore . I go to Singapore iBooks store ,there is all free books,I can't see any other books that I can purchase. But when I go to us iBooks store or other country's such as uk, they said my account can only be purchased in Singapore iBooks store. What can I do about it?

Due to copyright laws, publishers, and various other stuff, what is available in each country's iBooks Store varies, a lot. The only way to get books from the other stores is to get an account in that country. This is doable, and there are several threads on how to do it in the forum. Try the search feature in the forum. If that doesn't work hopefully some one else (who actually does this) will wander by to point you in the right direction.

You can also check out other apps to see if they are available. The Kindle app is popular, and has more books than iBooks if you can get it. Stanza is an alternate source for both paid and free books with several built in stores. No telling how long that will last with Apple enforcing it's new policies.

Sorry I don't know