compiling beep.c...
linking...
.\output\工程模板.axf: Error: L6218E: Undefined symbol delay (referred from beep.o).
.\output\工程模板.axf: Not enough information to list image symbols.
.\output\工程模板.axf: Finished: 1 information, 0 warning and 1 error messages.
Target not created
这是怎么回事?