#include <bits/stdc++.h>
using namespace std;
vector<long long> a;
long long n;
long long kad(int start) {
  int l = start;
  long long max_so_far = LLONG_MIN;
  long long mx = 0;
  int L, R;
  for (int i = start; i < n; i++) {
    if (i % 2 == 0)
      mx -= a[i];
    else
      mx += a[i];
    if ((i - l + 1) % 2 == 1) continue;
    if (mx > max_so_far) {
      max_so_far = mx;
      L = l, R = i;
    }
    if (mx < 0) {
      l = i + 1;
      mx = 0;
    }
  }
  if (max_so_far <= 0) {
    long long ans = 0;
    for (int i = 0; i < n; i++) ans += a[i] * (i % 2 == 0);
    return ans;
  }
  long long ans = 0;
  for (int i = 0; i < n; i++) {
    if (i >= L && i <= R)
      ans += a[i] * (long long)(i % 2 == 1);
    else
      ans += a[i] * (long long)(i % 2 == 0);
  }
  return ans;
}
int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  int t;
  cin >> t;
  while (t--) {
    cin >> n;
    a = vector<long long>(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    long long ans = kad(0);
    ans = max(ans, kad(1));
    cout << ans << '\n';
  }
}
