#include <bits/stdc++.h>
using namespace std;
#pragma optimise("-O3")
template <int D, typename T>
struct Vec : public vector<Vec<D - 1, T>> {
  static_assert(D >= 1, "Vector dimension must be greater than zero!");
  template <typename... Args>
  Vec(int n = 0, Args... args)
      : vector<Vec<D - 1, T>>(n, Vec<D - 1, T>(args...)) {}
};
template <typename T>
struct Vec<1, T> : public vector<T> {
  Vec(int n = 0, const T& val = T()) : vector<T>(n, val) {}
};
long long int power(long long int x, long long int y, long long int p) {
  long long int res = 1;
  x = x % p;
  if (y == 0) return 1;
  if (x == 0) return 0;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long int modinv(long long int a, long long int p) {
  return power(a, p - 2, p);
}
const int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1},
          dy[8] = {0, 1, 0, -1, -1, 1, -1, 1};
template <class T>
bool ckmin(T& a, T& b) {
  bool B = a > b;
  a = min(a, b);
  return B;
}
template <class T>
bool ckmax(T& a, T& b) {
  bool B = a < b;
  a = max(a, b);
  return B;
}
void solve() {
  long long int n;
  cin >> n;
  vector<long long int> a(n + 1);
  for (long long int i = 1; i <= n; i += 1) {
    cin >> a[i];
  }
  Vec<2, long long int> dp(n + 1, 4, 0);
  dp[0][0] = 0;
  dp[0][1] = 0;
  dp[0][2] = 0;
  dp[0][3] = 0;
  for (long long int i = 1; i <= n; i += 1) {
    if (i % 2) {
      dp[i][0] = dp[i - 1][0] + a[i];
      dp[i][1] = dp[i - 1][2];
      dp[i][2] = dp[i - 1][1];
      dp[i][3] = dp[i - 1][3] + a[i];
      dp[i][1] = max(dp[i][1], dp[i - 1][0]);
      dp[i][3] = max(dp[i - 1][2] + a[i], dp[i][3]);
    } else {
      dp[i][0] = dp[i - 1][0];
      dp[i][1] = dp[i - 1][2] + a[i];
      dp[i][2] = dp[i - 1][1] + a[i];
      dp[i][3] = dp[i - 1][3];
      dp[i][1] = max(dp[i][1], dp[i - 1][0] + a[i]);
      dp[i][3] = max(dp[i - 1][2], dp[i][3]);
    }
  }
  cout << max({dp[n][0], dp[n][2], dp[n][3]}) << '\n';
  return;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int T = 1;
  cin >> T;
  for (long long int c = 0; c < T; c++) {
    solve();
  }
  return 0;
}
