#include <bits/stdc++.h>
using namespace std;
long long int ANS = 0;
long long int mod = 1000000007;
int gcd(int a, int b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
int foo(int n) {
  if (n <= 0) return 1;
  return foo((n * 2) / 3) + foo(n - 2);
}
int go_l(string& s, int l, int r, char c, int napr) {
  int siz = r - l + 1;
  int ln, rn;
  int count = 0;
  if (siz == 1) {
    if (s[l] == c)
      return 0;
    else
      return 1;
  }
  if (napr == 0) {
    for (int i = l; i < l + siz / 2; ++i) {
      if (s[i] != c) count++;
    }
    ln = l + siz / 2;
    rn = r;
    return count + min(go_l(s, ln, rn, c + 1, 0), go_l(s, ln, rn, c + 1, 1));
  }
  if (napr == 1) {
    for (int i = l + siz / 2; i <= r; ++i) {
      if (s[i] != c) count++;
    }
    ln = l;
    rn = l + siz / 2 - 1;
    return count + min(go_l(s, ln, rn, c + 1, 0), go_l(s, ln, rn, c + 1, 1));
  }
}
int main() {
  int t, n;
  cin >> t;
  vector<long long int> a;
  vector<long long int> b;
  vector<long long int> c;
  while (t != 0) {
    --t;
    a.clear();
    b.clear();
    c.clear();
    cin >> n;
    a.resize(n);
    for (int i = 0; i < n; ++i) cin >> a[i];
    long long int sum = 0;
    long long int per = 0;
    for (int i = 0; i < n; i += 2) sum += a[i];
    for (int i = 0; i < n - 1; i += 2) {
      b.push_back(a[i + 1] - a[i]);
    }
    for (int i = 1; i < n - 1; i += 2) {
      c.push_back(a[i] - a[i + 1]);
    }
    long long int tmp = 0;
    for (int i = 0; i < b.size(); ++i) {
      if (b[i] > 0) {
        tmp += b[i];
        if (tmp > per) per = tmp;
        continue;
      }
      if (tmp > per) per = tmp;
      if (tmp + b[i] < 0)
        tmp = 0;
      else
        tmp += b[i];
    }
    tmp = 0;
    for (int i = 0; i < c.size(); ++i) {
      if (c[i] > 0) {
        tmp += c[i];
        if (tmp > per) per = tmp;
        continue;
      }
      if (tmp > per) per = tmp;
      if (tmp + c[i] < 0)
        tmp = 0;
      else
        tmp += c[i];
    }
    cout << sum + per << endl;
  }
  return 0;
}
