#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;

void solve() {
    int n;
    std::cin >> n;

    int cur = 0;
    std::vector<int> p;
    for(int i = 0; i < n; i ++ ) {
        if((cur ^ i) == 0) {
            if(i == n - 1) {
                std::cout << "imopssible" << '\n';
                return;
            }
            cur ^= (i + 1) ^ i;
            p.push_back(i + 1);
            p.push_back(i);
            i += 1;
        } else {
            cur ^= i;
            p.push_back(i);
        }
    }

    for(int i = 0; i < n; i ++ ) {
        std::cout << p[i] << " \n"[i == n - 1];
    }

}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int t = 1;
    std::cin >> t;
    
    while (t--) {
        solve();
    }
    
    return 0;
}