给定: 1. class TestA { 2. public void start() { System.out.println(“TestA”); } 3. } 4. public class TestB extends TestA { 5. public void start() { System.out.println(“TestB”); } 6. public static void main(String[] args) { 7. ((TestA)new TestB()).start(); 8. } 9. } 结果为?