#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// using namespace __gnu_pbds;
using namespace std;
typedef long long int ll;
// typedef vector<int> vi;
// typedef pair<int,int> pi;
/*After this, we can define a data structure indexed_set that is like set but can be
indexed like an array. The definition for int values is as follows:*/
// typedef tree<int,null_type,less<int>,rb_tree_tag,
// tree_order_statistics_node_update> indexed_set;
 
#define out cout<<"\n" 
// #define mnum pow(10,9)+7
// #define F first
// #define S second
// #define PB push_back
// #define MP make_pair
// #define f(i,n) for(i==;i<n;i++)
 
// Think before writing code,it saves lot of time and gives clarity
// Don't be sad you can do it _shiv_,its ok if u can't
ll max(ll a,ll b) { if(a>b) return a; return b; }
ll min(ll a,ll b) { if(a<b) return a; return b; }
bool cmp(ll a,ll b){return a>b; }
ll gcd(ll a,ll b) {if(a%b==0)return b; return gcd(b,a%b); }
int prime(int a) { 
    if(a==1||a==2) 
        return 0; 
    int arr[a+1]; 
    int ans=0;
        for(int i=2;i<=a;i++)
            arr[i]=1;
        
        for(int i=2;i*i<a;i++) {
            if(arr[i]==0) continue;
            for(int j=i*i;j<a;j+=i) {
                arr[j]=0;
            }
        }
        for(int i=2;i<a;i++) {
            if(arr[i]==1) ans++;
        }
         return ans;  
    }
 
 
void init_code() {
 
#ifndef ONLINE_JUDGE
 
freopen("input.txt", "r", stdin);
 
freopen("output.txt", "w", stdout);
 
#endif // ONLINE_JUDGE
 
} 


 
int main() {
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
init_code();
ll c,d,t,i,j,k,n,l,p,k1,k2,y,z,r,k3,q,w,h,A,B,a,b,m;
cin>>t;
while(t--) {
    cin>>n;
    ll arr[n];
    for(i=1;i<=n;i++) {
        arr[i-1]=i;
    }
    for(i=1;i<n;i++) {
        ll temp=arr[i-1];
        arr[i-1]=arr[i];
        arr[i]=temp;
        i++;
    }
    if(n%2==1) {
        ll temp=arr[n-1];
        arr[n-1]=arr[n-2];
        arr[n-2]=temp;
    }
    for(i=0;i<n;i++) {
cout<<arr[i]<<" ";
    }
    out;
}
return 0;
} 