forv i=1/`m'{
  bys year inid maolag aftermerge (q exp stkcd): g exps=exp[`i'] if !aftermerge
  bys year inid maolag aftermerge (q exp stkcd): g stkcds=stkcd[`i'] if !aftermerge
  bys year inid maolag aftermerge (q exp stkcd): replace q=. if exp==exps&_n>`i'
  bys year inid maolag aftermerge (q exp stkcd): replace q=. if stkcd==stkcds&_n>`i'
  drop exps stkcds
  }
invalid syntax
r(198);
输入上述命令后，总是出现invalid syntax，查找不出原因。请各位高手指教。非常感谢。