单项选择题
A.restore 400
B.restore 403
C.restore 453
D.Compilation fails.
E.An exception is thrown at runtime.
多项选择题 Which two statements are true if a NullPointerException is thrown on line 3 of class C？（）
单项选择题 Given a method that must ensure that its parameter is not null： What， inserted at line 12， is the appropriate way to handle a null value？（）
多项选择题 Which two code fragments are most likely to cause a StackOverflowError？（）
