在线等，C#调用C++ dll，里面结构体怎么声明处理？

C++ dll中有结构体
                struct WORKMODE {
                        byte cISINTPORT;
                        byte cINTMODE;
               ushort unCONTROLTIME;
                        };
                struct A_Context{
                                 byte      arr[4];
                                 WORKMODE  MyWorkMode[4];                                  
                                 }
我在C#中声明结构体A_Context
                struct A_Context{
                                [MarshalAs(UnmanagedType.ByValArray,SizeConst=4)]
                                 public byte[]     arr;                                ??????????
                                WORKMODE不会声明了  
                                ??????????                             
                                 }
这个WORKMODE类型应该怎么声明，望高人相助？