#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC target("sse4")
using namespace std;
const long long int MOD = 1e9 + 7;
const long long int MOD1 = 998244353;
const long long int N = 2e5 + 5;
const long long int INF = 1000111000111000111LL;
const long double EPS = 1e-12;
const long double PI = 3.141592653589793116;
long long int r1(vector<long long int> v) {
  long long int ans = 0;
  vector<long long int> dp;
  for (long long int i = 0; i + 1 < (long long int)((v).size()); i += 2) {
    dp.push_back(v[i + 1] - v[i]);
  }
  long long int n = (long long int)((dp).size());
  long long int cur = 0;
  for (long long int i = 0; i < n; i++) {
    cur += dp[i];
    if (cur < 0) cur = 0;
    ans = max(ans, cur);
  }
  return ans;
}
long long int r2(vector<long long int> v) {
  long long int ans = 0;
  vector<long long int> dp;
  for (long long int i = 1; i < (long long int)((v).size()); i += 2) {
    dp.push_back(v[i - 1] - v[i]);
  }
  long long int n = (long long int)((dp).size());
  long long int cur = 0;
  for (long long int i = 0; i < n; i++) {
    cur += dp[i];
    if (cur < 0) cur = 0;
    ans = max(ans, cur);
  }
  return ans;
}
void solve() {
  long long int n;
  cin >> n;
  vector<long long int> v(n);
  for (long long int i = (0); i < (n); i++) cin >> v[i];
  if (n == 1) {
    cout << v[0] << '\n';
    return;
  }
  vector<long long int> v1 = v;
  reverse((v1).begin(), (v1).end());
  v1.pop_back();
  reverse((v1).begin(), (v1).end());
  long long int sum = 0;
  for (long long int i = 0; i < n; i += 2) {
    sum += v[i];
  }
  cout << sum + max(r2(v1), r1(v)) << '\n';
}
int32_t main() {
  std::ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int T;
  cin >> T;
  while (T--) {
    solve();
  }
  return 0;
}
