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.\Objects\xinchengxu.axf: Error: L6218E: Undefined symbol mm_scan_GPIO_Config (referred from main_1.o).
.\Objects\xinchengxu.axf: Error: L6218E: Undefined symbol mm_scan (referred from main_1.o).
.\Objects\xinchengxu.axf: Error: L6218E: Undefined symbol SystemCoreClock (referred from delay.o).
.\Objects\xinchengxu.axf: Error: L6218E: Undefined symbol SystemInit (referred from startup_stm32f10x_hd.o).
These are Linker errors.
They tell you that you have called these functions, but have not defined them - hence, "undefined".
This usually happens when you #include a header which declares the names, but omit to add the file(s) with the definitions to your project.
The file(s) with the definitions could either be source files, or pre-built library files.
This is standard 'C' programming stuff - nothing specifically to do with Keil, ARM, or embedded.
http://c-faq.com/decl/decldef.html