请问高手老师,我怎么也找不出语句的错误
sql="select bh,xm,km,cj,bj,xq,xn"
  sql=sql & "from(SELECT student.bh,student.xm,student.bj,"
  sql=sql & "score.km,score.kt,score.zy,score.cy,score.sjys,"
  sql=sql & "score.sjys*0.3 as sjbl,score.llys,score.llys*0.4 as llbl,"
  sql=sql & "score.xq,score.kt+score.zy+score.cy+score.sjys*0.3 +score.llys*0.4 as cj,"
  sql=sql & "score.bz,score.xn FROM student,score WHERE  student.xh=score.xh"
  sql=sql & "and  xn='"& xn &"' and  xq='"& xq &"' and bj='"& bj &"'  and km='"& km &"') as a"
  sql=sql & "where cj<60  order BY bh,km"
  Rs.open sql,conn,3,1