单项选择题
Given: Which code, inserted at line 16, will cause a java.lang.ClassCastException?（）
A.Alpha a = x; B.Foo f = (Delta)x; C.Foo f = (Alpha)x; D.Beta b = (Beta)(Alpha)x;
单项选择题 Given: What is the result?（）
单项选择题 Given: What is the result when the go() method is invoked?（）
多项选择题 Given: Under which three circumstances will the code on line 37 be executed?（）
