#include <bits/stdc++.h>
using namespace std;
const long double pi = 3.14159265358979323846;
long long MOD = 1e9 + 7;
const char nl = '\n';
long long gcd(long long a, long long b) {
  if (a < b) return gcd(b, a);
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long min(long long a, long long b) {
  if (a < b) return a;
  return b;
}
long long max(long long a, long long b) {
  if (a > b) return a;
  return b;
}
long long sq(long long a) {
  long long ans = (1ll * a * a);
  return ans;
}
vector<int> Divisors(int n) {
  vector<int> a;
  for (int i = 1; i <= sqrt(n); i++) {
    if (n % i == 0) {
      if (n / i == i) {
        a.push_back(i);
      } else {
        a.push_back(i);
        a.push_back(n / i);
      }
    }
  }
  sort(a.begin(), a.end());
  return a;
}
void solve() {
  long long n;
  cin >> n;
  int i;
  long long a[n];
  long long even = 0;
  for (i = 0; i < n; i++) {
    cin >> a[i];
    if (i % 2 == 0) {
      even += a[i];
    }
  }
  long long f = 0;
  long long m = 0;
  for (i = 0; i < n - 1; i += 2) {
    m += a[i + 1] - a[i];
    f = max(f, m);
    if (m < 0) {
      m = 0;
    }
  }
  long long ff = 0;
  long long mm = 0;
  for (i = 1; i < n - 1; i += 2) {
    mm += a[i] - a[i + 1];
    ff = max(ff, mm);
    if (mm < 0) {
      mm = 0;
    }
  }
  cout << even + max(f, ff) << nl;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0), cout.tie(0);
  long long TC = 1;
  cin >> TC;
  while (TC--) {
    solve();
  }
}
