#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define endl '\n'
#define ll long long
#define ld long double
#define vi vector<ll>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define srt(v) sort(v.begin(),v.end())
#define rep(i, a, b) for(ll i = (a); i < (b); i++)
#define trace(x) cout<<#x<<": "<<x<<endl;
#define print(v) for(auto e:v) cout<<e<<" "; cout<<endl;
#define printp(v) for(auto e:v) cout<<e.first<<" "<<e.second<<endl;
const int N=5e5+10;
void solve() {
    ll n;cin>>n;
    vi p;
    ll ki = 2;
    ll ji = 1;
    if(n&1){
        vi q(n+1);
        rep(i,1,n+1){
            q[i] = i;
        }
        for (int i=1;i<=n-3; i+=2) {
            swap(q[i],q[i+1]);
        }
        q[n-2] = n-1;
        q[n-1] = n;
        q[n] = n-2;
        for(int i =1;i<=n;i++){
            cout<<q[i]<<' ';

        }
        cout<<endl;
    }
    else{
        for(int i = 0;i<n;i++){
            if(i&1){
                p.push_back(ji);
                ji+=2;
            }
            else{
                p.push_back(ki);
                ki+=2;

            }
        }
        print(p);
    }

    
}


int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int t=1;cin>>t;
    for(int i =1;i<=t;i++){
        solve();
    }
    return 0;
}