#include <bits/stdc++.h>
#pragma GCC optimize("O2")
using namespace std;
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
void solve() {
  long long n;
  cin >> n;
  vector<long long> a(n);
  for (long long i = 0; i < n; ++i) cin >> a[i];
  long long ans = 0;
  for (long long i = 0; i < n; i += 2) ans += a[i];
  vector<long long> tmp;
  for (long long i = 1; i + 1 < n; i += 2) {
    tmp.push_back(a[i] - a[i + 1]);
  }
  long long val = 0;
  long long x = 0;
  for (long long it : tmp) {
    x += it;
    val = max(val, x);
    if (x < 0) x = 0;
  }
  tmp.clear();
  x = 0;
  for (long long i = 1; i < n; i += 2) {
    tmp.push_back(a[i] - a[i - 1]);
  }
  for (long long it : tmp) {
    x += it;
    val = max(val, x);
    x = max(x, 0LL);
  }
  cout << ans + val << '\n';
}
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  long long t = 1;
  cin >> t;
  for (long long i = 1; i <= t; ++i) solve();
}
