设计一个抽象类程序，Teacher抽象类和Student抽象类对person抽象类具有继承关系，计算机老师具体类和英语老师具体类对Teacher抽象类具有继承关系，英语学生具体类和计算机学生具体类对Student抽象类具有继承关系，英语老师具体类和英语学生具体类要实现口语考级接口

抽象类程序如下：

public abstract class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public abstract void introduce();
}

public abstract class Teacher extends Person {
    private String subject;

    public Teacher(String name, int age, String subject) {
        super(name, age);
        this.subject = subject;
    }

    public abstract void teach();
}

public abstract class Student extends Person {
    private int grade;

    public Student(String name, int age, int grade) {
        super(name, age);
        this.grade = grade;
    }

    public abstract void study();
}

public interface OralExam {
    public void oralExam();
}

public class ComputerTeacher extends Teacher {
    public ComputerTeacher(String name, int age) {
        super(name, age, "Computer");
    }

    @Override
    public void introduce() {
        System.out.println("I am a computer teacher.");
    }

    @Override
    public void teach() {
        System.out.println("I teach computer.");
    }
}

public class EnglishTeacher extends Teacher implements OralExam {
    public EnglishTeacher(String name, int age) {
        super(name, age, "English");
    }

    @Override
    public void introduce() {
        System.out.println("I am an English teacher.");
    }

    @Override
    public void teach() {
        System.out.println("I teach English.");
    }

    @Override
    public void oralExam() {
        System.out.println("I can conduct oral exams for English learners.");
    }
}

public class ComputerStudent extends Student {
    public ComputerStudent(String name, int age, int grade) {
        super(name, age, grade);
    }

    @Override
    public void introduce() {
        System.out.println("I am a computer student.");
    }

    @Override
    public void study() {
        System.out.println("I study computer.");
    }
}

public class EnglishStudent extends Student implements OralExam {
    public EnglishStudent(String name, int age, int grade) {
        super(name, age, grade);
    }

    @Override
    public void introduce() {
        System.out.println("I am an English student.");
    }

    @Override
    public void study() {
        System.out.println("I study English.");
    }

    @Override
    public void oralExam() {
        System.out.println("I take oral exams for English proficiency.");
    }
}

其中，Person抽象类表示人，Teacher和Student抽象类表示老师和学生，英语老师和英语学生需要实现OralExam接口，计算机老师和计算机学生不需要实现该接口。具体类ComputerTeacher、EnglishTeacher、ComputerStudent、EnglishStudent分别表示计算机老师、英语老师、计算机学生、英语学生。每个类都有自己的介绍方法，教学方法或学习方法，并且英语老师和英语学生都实现了OralExam接口的方法。