多项选择题
Given: Which three are valid?（）
A.p0 = p1; B.p1 = p2; C.p2 = p4; D.p2 = (ClassC)p1; E.p1 = (ClassB)p3; F.p2 = (ClassC)p4;
单项选择题 Given: What is the result?（）
单项选择题 Given: What is the result? （）
