标题：请找出这个语句的毛病，如何修改

n:=rand(2);

if n=1 then

BUY(n=1,手数,MARKET);

  if BARSLAST(n=1)=3 and DYNAINFO(211)<= CLOSE then SELL(DYNAINFO(211)<= CLOSE,手数,MARKET);

  ElseIF BARSLAST(n=1)>3 and REF(CLOSE,3)> CLOSE then SELL(REF(CLOSE,3)> CLOSE,手数,MARKET);

End

请找出这个语句的毛病，如何修改

 n:=rand(2);
len:BARSLAST(n=1);
ref_c:REF(CLOSE,3);
if n=1 then
begin
BUY(n=1,手数,MARKET);
if len=3 and DYNAINFO(211)<= CLOSE
then
SELL(DYNAINFO(211)<= CLOSE,手数,MARKET);
else IF len>3 and ref_c> CLOSE then SELL(ref_c>CLOSE,手数,MARKET);