#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
#define run  ios_base::sync_with_stdio(false);cin.tie(0);

#define ln length()
#define ll long long
#define pll pair<ll, ll>
#define ull unsigned ll
#define ld long double
#define endl "\n"
#define pb push_back
#define fi first
#define se second
 
#define pi acos(-1)
#define N 107
#define INF 10000000000000000
#define minimum -9000000000000000000
#define maximum -minimum
#define mod 998244353
 
using namespace std;

//using namespace __gnu_pbds;
//template <class t>
//using ordered_set=tree<t, null_type,less<t>, rb_tree_tag,tree_order_statistics_node_update>;

//mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

ll gcd(ll a, ll b)
{
	if(b==0)
		return a;
	return gcd(b, a%b);
}

ll lcm(ll a, ll b)
{
	return a/gcd(a, b)*b;
}

bool isprime(ll n)
{
	if(n==1)
		return 1;
	for(ll i=2; i*i<=n; i++)
	{
		if(n%i==0)
			return 0;
	}
	return 1;
}
 
ll binpow(ll a, ll b)
{
    a%=mod;
    ll res=1;
    while(b>0)
	{
        if(b%2==1)
            res=(res*a)%mod;
        a=(a*a)%mod;
        b/=2;
    }
    return res;
}

int main()
{
	run;
	ll t;
	cin>>t;
	while(t--)
	{
		ll n;
		cin>>n;
		vector<ll>v;
		for(ll i=2; i<=n; i+=2)
		{
			v.pb(i);
			v.pb(i-1);
		}
		if(n%2==0)
		{
			for(ll i:v)
			{
				cout<<i<<" ";
			}
			cout<<endl;
		}
		else
		{
			for(ll i=0; i<n-3; i++)
			{
				cout<<v[i]<<" ";
			}
			cout<<v[n-3]<<" "<<n<<" "<<v[n-2]<<endl;
		}
	}
}
// By Xanlar