#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    ll sum = 0;
    vector<vector<ll>> dp(n);
    vector<ll> v(n);
    for (ll i = 0; i < n; ++i) {
      cin >> v[i];
      sum += v[i] * ((i + 1) % 2);
      dp[i].push_back(0);
      dp[i].push_back(0);
    }
    if (n == 1) {
      cout << sum << endl;
    } else {
      dp[1][1] = max(dp[1][1], -v[0] + v[1]);
      dp[1][0] = max(dp[0][0], dp[1][1]);
      for (int i = 2; i < n; ++i) {
        if (i % 2 == 0) {
          dp[i][1] = max(dp[i - 2][1] - v[i] + v[i - 1], dp[i][1]);
          dp[i][0] = max(dp[i - 1][0], dp[i][1]);
        } else {
          dp[i][1] = max(dp[i - 2][1] + v[i] - v[i - 1], dp[i][1]);
          dp[i][0] = max(dp[i - 1][0], dp[i][1]);
        }
      }
      cout << dp[n - 1][0] + sum << endl;
    }
    dp.clear();
    v.clear();
  }
}
