#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <ctime>
#include <cmath>
#define ll long long
using namespace std;
int n,T;
int a[1020];
const int MOD = 1000000007;
int get(){
    char t=getchar();
    while(t<'0'||t>'9')t=getchar();
    int x = 0;
    while(t>='0'&&t<='9'){
        x*=10;
        x+=t-'0';
        t=getchar();
    }
    return x;
}
int main(){
    ll aug = 1;
    ll p1 = MOD - 2;
    ll p2 = 2;
    ll p3 = 1;
    while(p1 > 0){
        if((p1 & p3) > 0){
            p1 -= p3;
            aug *= p2;
            aug %= MOD;
        }
        p2 *= p2;
        p3 *= 2;
        p2 %= MOD;

    }
    //freopen("E.out","w",stdout);
    T = get();
    for(int ii=1;ii<=T;++ii){
        int n=get();
        int flag1 = 0;
        for(int i=1;i<=n;++i){
            a[i]=get();
            flag1 += a[i];
        }
        flag1 /= 2;
        int flag2 = 0;
        for(int i=2;i<=n;++i){
            flag2 += a[i-1]+a[i];
        }
        ll ans = flag1;
        ll ans2 = flag2 / 2;
        ans2 = ans2 * aug % MOD;
        ans = (ans - ans2 + MOD) % MOD;
        cout << ans << endl;
        
    }
    return 0;
}