#include<bits/stdc++.h>
using namespace std;

const int N=1e6+100;
#define gc getchar()
#define rd read()
inline int read(){
	int x=0,f=0; char c=gc;
	for(;c<'0'||c>'9';c=gc) f|=(c=='-');
	for(;c>='0'&&c<='9';c=gc) x=(x<<1)+(x<<3)+(c^48);
	return f?-x:x;
}

int n,a[N];
inline int chk(){
	for(int i=0,lst=0;i<n;++i){
		lst^=a[i];
		if(!lst) return 1;
	}
	return 0;
}
void solve(){
	n=rd; if(n==1) return printf("impossible\n"),void();
	a[0]=1,a[1]=0; for(int i=2;i<n;++i) a[i]=i;
	if(chk()) printf("impossible\n");
	else{ for(int i=0;i<n;++i) printf("%d ", a[i]); puts(""); }
}

int main(){
	
	int T=rd;
	while(T--) solve();
	
	return 0;
}