#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return (b == 0) ? a : gcd(b, a % b); }
long long power(long long x, long long p) {
  if (p == 0) return 1;
  if (p == 1) return x;
  if (p % 2) return x * power(x, p - 1);
  long long y = power(x, p / 2);
  return y * y;
}
void solve() {
  long long n;
  cin >> n;
  long long arr[n];
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
  }
  pair<long long, long long> modd, meven;
  long long odd = 0, even = 0, l = -1, r = -1, res = 0;
  for (int i = 0; i < n; i++) {
    if (i % 2)
      odd += arr[i];
    else
      even += arr[i];
    long long cur = odd - even;
    pair<long long, long long> p;
    if (i % 2)
      p = meven;
    else
      p = modd;
    long long val = cur - p.first;
    if (val > res) {
      l = p.second;
      r = i;
      res = val;
    }
    long long x = odd - even + arr[i] * (i % 2 ? -1 : 1);
    if (i % 2 == 0) {
      if (x < meven.first) meven = make_pair(x, i);
    } else {
      if (x < modd.first) modd = make_pair(x, i);
    }
  }
  if (l != -1) {
    for (int i = 0; i < (r - l + 1) / 2; i++) {
      swap(arr[l + i], arr[r - i]);
    }
  }
  odd = 0;
  even = 0;
  for (int i = 0; i < n; i++) {
    if (i % 2)
      odd += arr[i];
    else
      even += arr[i];
  }
  cout << max(odd, even) << endl;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t;
  cin >> t;
  while (t--) solve();
}
