#include <vector>
#pragma GCC target ("avx2")
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

#define A(a) begin(a),end(a)
#define pb push_back
#define pp partition_point
#define K first
#define V second
#define krep(i,a,b) for (int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int) (size(x))

template <typename T>
std::istream& operator >>(std::istream& input, std::pair <T, T> & data)
{
    input >> data.first >> data.second;
    return input;
}
template <typename T>
std::istream& operator >>(std::istream& input, std::vector<T>& data)
{
    for (T& x : data)
        input >> x;
    return input;
}
template <typename T>
std::ostream& operator <<(std::ostream& output, const pair <T, T> & data)
{
    output << "(" << data.first << "," << data.second << ")";
    return output;
}
template <typename T>
std::ostream& operator <<(std::ostream& output, const std::vector<T>& data)
{
    for (const T& x : data)
        output << x << " ";
    return output;
}
struct chash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
template<typename T, typename U> using pb_map = gp_hash_table<T, U, chash>;
template<typename T> using pb_set = gp_hash_table<T, null_type, chash>;
using ll = long long;
using ld = long double;
using vi = vector<int>;
using vii = vector<vector<int>>;
using vll =  vector<ll>;
using pll = pair<ll,ll>;
using pii = pair<int,int>;
template<class T> bool ckmin(T& a, const T& b) { return b < a ? (a = b, 1) : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? (a = b, 1) : 0; }
inline long long Bit(long long mask, long long bit) { return (mask >> bit) & 1; }


constexpr ll NN = 2e5, M = 1000000007, L = 20;

void run()
{
    ll n; cin >> n;
    if(n%2 == 0){
        for(int i = 1;i<=n;i+=2){
            cout << i+1 << " " << i << " ";
        }
        cout << '\n';
    }else{
        for(int i = 1;i<=n-3;i+=2) cout << i+1 << " " << i << " ";
        cout << n-1 << " " << n << " " << n-2 << '\n';
    }
}

int main()
{
    //KING OF THE WORLD...... U.W.T.B
    //nick belov always reads the entire problem statement.
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    int t; cin>>t; while(t--) run();
}