#include <bits/stdc++.h>
using namespace std;
int t;
int n;
int a[200005];
long long oddpre[100005];
long long evenpre[100005];
long long delta1[100005];
long long delta2[100005];
long long sufmx1[100005];
long long sufmx2[100005];
int main() {
  for (cin >> t; t--;) {
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];
    for (int i = 1; i <= n; i++) {
      if (i & 1)
        evenpre[(i + 1) / 2] = evenpre[i / 2] + a[i];
      else
        oddpre[i / 2] = oddpre[(i - 1) / 2] + a[i];
    }
    for (int i = 1; i <= n / 2; i++) delta1[i] = oddpre[i] - evenpre[i];
    for (int i = 1; i <= (n - 1) / 2; i++)
      delta2[i] = oddpre[i] - evenpre[i + 1];
    sufmx1[n / 2] = delta1[n / 2];
    for (int i = n / 2 - 1; i >= 0; i--)
      sufmx1[i] = max(delta1[i], sufmx1[i + 1]);
    sufmx2[(n - 1) / 2] = delta2[(n - 1) / 2];
    for (int i = (n - 1) / 2 - 1; i >= 0; i--)
      sufmx2[i] = max(delta2[i], sufmx2[i + 1]);
    long long ans = 0;
    for (int i = 1; i < n; i++) {
      if (i & 1)
        ans = max(ans, evenpre[i / 2] - oddpre[i / 2] + sufmx1[i / 2]);
      else
        ans = max(ans, evenpre[i / 2] - oddpre[i / 2 - 1] + sufmx2[i / 2]);
    }
    cout << ans + evenpre[(n + 1) / 2] << endl;
  }
  return 0;
}
