#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int t;
  cin >> t;
  while (t--) {
    long long int n;
    cin >> n;
    long long int a[n];
    long long int sum = 0;
    for (int i = 0; i < n; i++) {
      cin >> a[i];
      if (!(i & 1)) sum += a[i];
    }
    long long int best = 0;
    long long int cur = 0;
    long long int z, z1;
    if (n & 1)
      z = n - 1;
    else
      z = n;
    for (int i = 0; i < z; i += 2) {
      cur = max(0ll, cur + a[i + 1] - a[i]);
      best = max(cur, best);
    }
    cur = 0;
    if (!(n & 1))
      z1 = n - 1;
    else
      z1 = n;
    for (int i = 1; i < z1; i += 2) {
      cur = max(0ll, cur + a[i] - a[i + 1]);
      best = max(cur, best);
    }
    cout << sum + best << endl;
  }
}
