#include<bits/stdc++.h>
using namespace std;
int main()
{
int t, n, q, l, r;
cin>>t;
string s, res;
char prefix, suffix;
while (t--)
{
cin>>n>>q;
cin>>s;
while (q--)
{
cin>>l>>r;
l -= 1;
r -= 1;
prefix = s[l];
suffix = s[r];
res = "NO\n";
for (int i=0; i<l; i++)
{
if (s[i] == prefix)
{
res = "YES\n";
break;
}
}
for (int i=r+1; i<n; i++)
{
if (s[i] == suffix)
{
res = "YES\n";
break;
}
}
cout<<res;
}
}
return(0);
}
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