"I eat half of the bread."
Translation:Tôi ăn nửa cái bánh mì.
I think the use of "of" in this sentence should be optional. In the US you can just say "I eat half the bread..." if you're talking about a specific known quantity during a specific timeframe. "Of" becomes optional in casual speak. E.g. I eat half the bread in the morning and half at night.