多选题 Given:
2. class Pancake { }
3. class BlueberryPancake extends Pancake { }
4. public class SourdoughBlueberryPancake2 extends BlueberryPancake {
5. public static void main(String[] args) {
6. Pancake p4 = new SourdoughBlueberryPancake2();
7. // insert code here
8. } }
And the following six declarations (which are to be inserted independently at line 7):
Ⅰ. Pancake p5 = p4;
Ⅱ. Pancake p6 = (BlueberryPancake)p4;
Ⅲ. BlueberryPancake b2 = (BlueberryPancake)p4;
Ⅳ. BlueberryPancake b3 = (SourdoughBlueberryPancake2)p4;
Ⅴ. SourdoughBlueberryPancake2 s1 = (BlueberryPancake)p4;
Ⅵ. SourdoughBlueberryPancake2 s2 = (SourdoughBlueberryPancake2)p4;
Which are true? (Choose all that apply.)

A、 All six declarations will compile.
B、 Exactly one declaration will not compile.
C、 More than one of the declarations will not compile.
D、 Of those declarations that compile, none will throw an exception.
E、 Of those declarations that compile, exactly one will throw an exception.
F、 Of those declarations that compile, more than one will throw an exception.

【正确答案】 B、D

【答案解析】