#include <bits/stdc++.h>
using namespace std;
int main() {
  int t, n, m, i, j;
  cin >> t;
  while (t--) {
    cin >> n >> m;
    for (i = 0; i < n; i++) {
      for (j = 0; j < m - 1; j++) {
        cout << "B";
      }
      if (i == 0) {
        cout << "B\n";
      } else {
        cout << "W\n";
      }
    }
  }
  return 0;
}
