RT，请问这个是什么原因呢？如何解决？
> A=rep("F",5)
> B=rep("M",5)
> C=c(1:5)
> D=c(14,16,15,17,15,14,16,14,15,16)
> E=c(156,158,161,156,153,162,157,159,163,165)
> F=c(42.3,45.0,48.5,51.5,44.6,48.8,46.7,49.9,50.2,53.7)
> G=data.frame(序号=C,性别=c(A,B),年龄=D,身高=E,体重=F)
> write.table(G,file="data_frame.txt",quote=FALSE)
Error in file(file, ifelse(append, "a", "w")) :
  cannot open the connection
In addition: Warning message:
In file(file, ifelse(append, "a", "w")) :
  cannot open file 'data_frame.txt': Permission denied