实现效果：
知识运用：(泛型类的继承)
class DerivedClass<类型参数T>:BaseClass<类型参数T>
{
}
实现代码：
class BstuInfo<T>
{
public T Num;
public T Name;
public T Sex;
public T Age;
public T Birthday;
public T Salary;
}
class HstuInfo<T>:BstuInfo<T>
{
public T Chinese;
public T Match;
public T English;
}
