#include <bits/stdc++.h>
using namespace std;
//---------------------------------- -x------------------------------------
const long long mod = 1e9 + 7;
const double PI = 2 * acos(0.0);
typedef vector<long long> vll;
typedef long double lld;
typedef long long ll;
typedef unsigned long long ull;
#define tc  ll t=1;  cin>>t; while(t--)
#define f(i,a,n) for(i=a;i<n;i++)
#define f1(i,a,n) for(i=a;i<=n;i++)
#define all(a) a.begin(),a.end()
#define lb lower_bound
#define ub upper_bound
#define fio ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define S second
#define F first
#define pb push_back
//---------------------------------- -x------------------------------------
void _print(ll t) {cerr << t;}
void _print(int t) {cerr << t;}
void _print(string t) {cerr << t;}
void _print(char t) {cerr << t;}
void _print(lld t) {cerr << t;}
void _print(double t) {cerr << t;}
void _print(ull t) {cerr << t;}

template <class T, class V> void _print(pair <T, V> p);
template <class T> void _print(vector <T> v);
template <class T> void _print(set <T> v);
template <class T, class V> void _print(map <T, V> v);
template <class T> void _print(multiset <T> v);
template <class T, class V> void _print(pair <T, V> p) {cerr << "{"; _print(p.ff); cerr << ","; _print(p.ss); cerr << "}";}
template <class T> void _print(vector <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
template <class T> void _print(set <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
template <class T> void _print(multiset <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void _print(map <T, V> v) {cerr << "[ "; for (auto i : v) {_print(i); cerr << " ";} cerr << "]";}

//---------------------------------- -x------------------------------------
#ifndef ONLINE_JUDGE
#define debug(x) cerr << #x <<" = "; _print(x); cerr << endl;
#else
#define debug(x)
#endif

//---------------------------------- -x------------------------------------
ll power(ll x, ll n)
{
    ll res = 1;
    while (n)
    {
        if (n & 1)
            res = res * x % mod;
        n = n / 2;
        x = x * x % mod;
    }
    return res % mod;
}
//---------------------------------- -x------------------------------------

long long modinv(long long n)
{
    return power(n, mod - 2);
}
//---------------------------------- -x------------------------------------


void solve()
{
    ll n;
    cin >> n;
    ll i;
    if (!(n & 1)) {
        for (int i = 1; i <= n; i += 2) {
            cout << i + 1 << " " << i << " ";
        }
    }
    else {
        for (int i = 1; i <= n - 3; i += 2) {
            cout << i + 1 << " " << i << " ";
        }
        cout << n << " " << n - 2 << " " << n - 1;
    }
}

//---------------------------------- -x---------------------------------- -
int main()
{
#ifndef ONLINE_JUDGE
    freopen("Error.txt", "w", stderr);
#endif
    fio;
    tc
    {
        solve();
        cout << endl;
    }
    return 0;
}