predicate logic problem

[facepuncher]

hey all. a friend of mine who is also interested in logical philosophy bet me i couldn't translate a sentence into predicate logic, and obviously im trying to prove him wrong. the sentence is as follows...

some bears attack people. not all bears who attack people are carnivores, but all bears who attack people are dangerous. therefore, there are some non-carnivorous bears that are dangerous.

using Bx: x is a bear, Ax: x attacks people, Cx: x is a carnivore and Dx: x is dangerous, could anyone shed some insight to the problem? i've come back to him with a few suggestions but he's kindly shown me how they were wrong without telling me the right answer.

[humphrz]

(=x) will be there exists some x
(\/x) will be for all x

(=x)(\/y)[[Bx AND Ax] AND [(Bx AND Ax AND Cx') AND (By AND Ay -> Dy)] -> [Bx AND Cx' AND Dx]]

I am new to this stuff so my logic might be a little off.