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

int solve(){
    int n;
    cin>>n;
    vector<int> a(n);
    for(int i = 0; i < n; i++){
        a[i] = i+1;
    }
    for(int i = 0; i < n - 1; i+=2){
        swap(a[i], a[i+1]);
    }
    if(n%2 == 1){
        swap(a[n-1], a[n-2]);
    }
    for(auto it: a){
        cout<<it<<" ";
    }
    cout << endl;
    return 0;
}
int32_t main(){
    ios::sync_with_stdio(false); 
    cin.tie(0); cout.tie(0);
 
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
    

    int t;
    t = 1;
    cin>>t;
    while(t--){
        solve();
    }
    return 0;
}