一个句子。帮我看下语法对不对。

were改为was
angle改为angel，并在前面加上a。
所以整句话就是
I believed that there was a angel in the world 。

I used to believe that there would be angels in the world.

I ever believed that there were angel in the world.

I believed that there was an angel in the world.

I believe that there is a angel in the world 。

Once I believed that there were angel in the world.^-^我曾经相信世界上有天使存在 对吧~