#include<iostream>
#include<cmath>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<queue>
#include<vector>
#define int long long
using namespace std;
const int p=1e9+7;
const int INF=2147483647;
inline int read()
{
    int neg=1,num=0;char c=getchar();
    for(;!isdigit(c);c=getchar())if(c=='-')neg=-1;
    for(;isdigit(c);c=getchar())num=(num<<1)+(num<<3)+c-'0';
    return neg*num;
}
int T,n,ans,a[1010];
inline int Pow(int x,int y){int sum=1;for(;y;y>>=1,x=x*x%p)if(y&1)sum=sum*x%p;return sum;}
signed main()
{
    T=read();
    while(T--)
    {
        n=read();ans=0;
        for(int i=1;i<=n;i++)a[i]=read();
        printf("%lld\n",((a[1]+a[n])*Pow(4,p-2)%p+p)%p);
    }
    return 0;
}