如何修复获取CS1518：预期的类，委托，枚举，接口或结构错误

Question

如何修复获取CS1518：预期的类，委托，枚举，接口或结构错误

{       ImplementsSystem.ComponentModel.INotifyPropertyChanging.PropertyChanging;
        ImplementsSystem.ComponentModel.INotifyPropertyChanged.PropertyChanged;


        public event PropertyChangingEventHandler PropertyChanging;

        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void SendPropertyChanging();
        }

        {

        if (((this.PropertyChangingEvent == null) == false)) {
                if (PropertyChanging != null) {
                    RaiseEventPropertyChanging(this, emptyChangingEventArgs);    

                }
            }
        } 


        protected virtual void SendPropertyChanged(String propertyName) {
        if (((this;PropertyChangedEvent == null) 
                    == false)) {
            RaiseEventPropertyChanged(this, new PropertyChangedEventArgs(propertyName));
                }
            }
        }
    }
}