#include <bits/stdc++.h>
using namespace std;
const long long N = 2e5 + 3, mod = 1e9 + 7, inf = 3e18 + 7;
long long tc, n, m, a, b, c, d, i, j, k;
long long A[N], odd[N], even[N];
string s[N];
vector<long long> vec;
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  cin >> tc;
  while (tc--) {
    cin >> n;
    long long sum = 0, ans = 0, mx;
    for (i = 1; i <= n; i++) cin >> A[i], sum += (i % 2 ? A[i] : 0);
    A[n + 1] = A[n];
    for (i = 2; i <= n; i += 2) even[i] = even[i - 2] + A[i] - A[i - 1];
    for (i = 2; i <= n; i += 2) odd[i] = odd[i - 2] + A[i] - A[i + 1];
    if (n % 2) n--;
    for (i = n, mx = even[n]; i > 0; i -= 2)
      mx = max(mx, even[i]), ans = max(ans, mx - even[i - 2]);
    for (i = n, mx = odd[n]; i > 0; i -= 2)
      mx = max(mx, odd[i]), ans = max(ans, mx - odd[i - 2]);
    cout << ans + sum << endl;
  }
}
