#include<bits/stdc++.h>

using namespace std;

#define ll long long
#define int long long
#define mod 1000000007
#define modulo 998244353
#define endl "\n"
#define pb push_back
#define mp make_pair
#define Max(x,y,z) max(x,max(y,z))
#define Min(x,y,z) min(x,min(y,z))
#define fr(i,s,e) for(i=s;i<e;i++)
#define rf(i,s,e) for(i=s-1;i>=e;i--)
#define ff first
#define ss second
#define IOS ios_base::sync_with_stdio(false); cin.tie(NULL);
typedef vector<int> vi;
typedef pair<int,int> pi;

int dp[200005]={0};
//int dp[35][35]={0};
int b[200005]={0};
int c[500005]={0};
int a[500005]={0};
int nod[200005]={0};
//int temp[500005]={0};
int v[500005]={0};
int t[200005]={0};
int power(int x, unsigned int y) 
{ 
    if (y == 0) 
        return 1; 
    else if (y % 2 == 0) 
        return power(x, y / 2) * power(x, y / 2); 
    else
        return x * power(x, y / 2) * power(x, y / 2); 
} 
 bool prime[405]; 


int32_t main()
{
       IOS;
     //freopen("input.txt", "r", stdin);
     //freopen("output.txt", "w", stdout);
      int x=0,m,y,n,cnt=0;
      string s;
       int q;
       cin>>cnt;
       
       while(cnt--)
       {
        cin>>n;
       cin>>q;
       cin>>s;

        while(q--)
       {

        int w,x=0,y=0,k=0,z=0,sum=0,g,r,l,t,d,pos=-1,m,a,b;
        
        cin>>l>>r;
        if((r-l+1)<2)
        {
          cout<<"NO"<<endl;
          continue;
        }

        char c=s[l-1];
        bool val=false;
        for (int i = 0; i < (l-1); ++i)
        {
         if(c==s[i])
         {
          val=true;
          break;
         }
        }
        c=s[r-1];
        for (int i = r; i < n; ++i)
        {
          if(s[i]==c)
          {
            val=true;
            break;
          }
          
        }
        if(val)
        {
          cout<<"YES"<<endl;
        }
        else
        {
          cout<<"NO"<<endl;
        }
        
        
   }

       }

      
       

        
    


       
    return 0;
        
    
}