#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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Mgo2IDMKMDAxMDAwCjIgNAoxIDMKMyA1CjQgMgoxMTExCjEgNAoyIDMK

2
6 3
001000
2 4
1 3
3 5
4 2
1111
1 4
2 3