"I am prohibited from drinking alcohol."
Translation:Tôi bị cấm uống rượu.
Similar to the Chinese usage, bị is for negative actions/consequences while được is for positive ones.
Tôi bị ngã/té = I fell down
Tôi được thưởng một món quà = I was given a gift
I think theres also an element of possibility in the difference as well...wither an action needs someone to carry it out or wither it could do it itself...lốp bị thay đổi. tay tôi được rửa sạch. The tyre is changed. My hands are washed.
Who knows? I can't remember!!!
from here has the meaning of prevention not the origine, it cannot be translated as "từ" (from) or "bởi" (because of).
why don't you write the whole sentence so we could understand how it is used and then give you some explanation..?
Again, native Vietnamese here. Native speakers NEVER say "Tôi bị cấm đoán khỏi uống rượu" (as suggested by Duolingo). Rather, there are a lot of translation possibilities:
Tôi không được phép uống rượu
Tôi bị cấm không được uống rượu
Tôi không được uống rượu.