which在主语从句中做成分不

作
主语 Which is right hasn't been decided。
定语修饰名词 Which picture is better is not known。
再问： in some countries, ____are called "public schools" are not owned by the public。 A which B as C what D that 这里选C 是由于其是 泛指 而不是 特指 才选 C 的吗？