請問在keil編譯過后顯示以下情況，該怎么解決 *** WARNING L1: UNRESOLVED EXTERNAL SYMBOL     SYMBOL:  ?C_START     MODULE:  STARTUP.obj (?C_STARTUP) *** WARNING L2: REFERENCE MADE TO UNRESOLVED EXTERNAL     SYMBOL:  ?C_START     MODULE:  STARTUP.obj (?C_STARTUP)     ADDRESS: 080AH Program Size: data=9.0 xdata=0 code=15 creating hex file from "fz"... "fz" - 0 Error(s), 2 Warning(s).