#include <iostream>

using namespace std;
int t,n;
int main()
{
    cin>>t;
    while (t)
    {
    t--;
    cin>>n;
    if (n%2==0)
    {
        for (int i=1; i<=n; i++)
        if (i%2==1) cout<<i+1<<" ";
        else cout<<i-1<<" ";
    }
    else
    {
        for (int i=1; i<=n-3; i++)
        if (i%2==1) cout<<i+1<<" ";
        else cout<<i-1<<" ";
        cout<<n-1<<" "<<n<<" "<<n-2;
    }
    cout<<'\n';
    }

    return 0;
}