SQL Error: select id,classid,ttid,onclick,plnum,totaldown,newspath,filename,userid,username,firsttitle,isgood,ispic,istop,isqf,ismember,isurl,truetime,lastdotime,havehtml,groupid,userfen,titlefont,titleurl,stb,fstb,restb,keyboard,eckuid,title,titlepic,newstime,fenlei,fenlei_id,kemu,kemu_id,tixing,nandu,zj,zj_id,paper_id,questions from ***_ecms_tiku where (classid='96') order by rand() DESC limit 6
，但当原点在L内时，由于P、Q不满足在单连通域内有一阶连续偏导数的条件，故只有原点在D外时，曲线积分才与路径无关，此时I＝0。
