/* e.cpp */
#include <bits/stdc++.h>

using i64 = long long;

struct DSU {
    std::vector<int> fa, sz;
    DSU(int n = 0) { init(n); }
    void init(int n) {
        fa.resize(n), std::iota(fa.begin(), fa.end(), 0);
        sz.assign(n, 1);
    }
    int find(int x) {
        while (x != fa[x]) x = fa[x] = fa[fa[x]];
        return x;
    }
    bool same(int x, int y) { return find(x) == find(y); }
    bool merge(int x, int y) {
        if ((x = find(x)) == (y = find(y))) return false;
        return sz[x] += sz[y], fa[y] = x, true;
    }
    int size(int x) { return sz[find(x)]; }
};

template <typename T> constexpr T power(T a, i64 b) {
    T c{1}; for (; b; b /= 2, a *= a) if (b & 1) c *= a;
    return c;
}
template <int P> struct MInt {
    int x;
    constexpr MInt() : x{} {}
    constexpr MInt(i64 x_) : x{norm(x_ % getMod())} {}
    static int Mod;
    constexpr static int getMod() { return P > 0 ? P : Mod; }
    constexpr static void setMod(int Mod_) { Mod = Mod_; }
    constexpr int up(int x) const {
        if (x < 0) x += getMod();
        return x;
    }
    constexpr int down(int x) const {
        if (x >= getMod()) x -= getMod();
        return x;
    }
    constexpr int norm(int x) const {
        return up(down(x));
    }
    constexpr int val() const { return x; }
    explicit constexpr operator int() const { return x; }
    constexpr MInt operator-() const {
        MInt res; res.x = norm(getMod() - x); return res;
    }
    constexpr MInt inv() const {
        assert(x != 0);
        return power(*this, getMod() - 2);
    }
    constexpr MInt &operator+=(MInt rhs) & { return x = down(x + rhs.x), *this; }
    constexpr MInt &operator-=(MInt rhs) & { return x = up(x - rhs.x), *this; }
    constexpr MInt &operator*=(MInt rhs) & { return x = 1ll * x * rhs.x % getMod(), *this; }
    constexpr MInt &operator/=(MInt rhs) & { return *this *= rhs.inv(); }
    friend constexpr MInt operator+(MInt lhs, MInt rhs) { return lhs += rhs; }
    friend constexpr MInt operator-(MInt lhs, MInt rhs) { return lhs -= rhs; }
    friend constexpr MInt operator*(MInt lhs, MInt rhs) { return lhs *= rhs; }
    friend constexpr MInt operator/(MInt lhs, MInt rhs) { return lhs /= rhs; }
    friend constexpr bool operator==(MInt lhs, MInt rhs) { return lhs.val() == rhs.val(); }
    friend constexpr bool operator!=(MInt lhs, MInt rhs) { return lhs.val() != rhs.val(); }
    friend constexpr std::istream &operator>>(std::istream &is, MInt &a) {
        i64 x = 0; is >> x, a = MInt(x); return is;
    }
    friend constexpr std::ostream &operator<<(std::ostream &os, const MInt &a) {
        return os << a.val();
    }
};

template <int P> int MInt<P>::Mod = P;
template <> int MInt<0>::Mod = 1;
template <int V, int P> constexpr MInt<P> CInv = MInt<P>(V).inv();

constexpr int P = 1011451423;
using Z = MInt<P>;

constexpr Z B = 31;

void solve() {
    int n, m;
    std::cin >> n >> m;
    
    std::vector<std::string> a(n);
    for (int i = 0; i < n; ++i) {
        std::cin >> a[i];
    }

    Z x = power(B, m - 1);
    std::map<int, int> mp;
    DSU dsu(n);
    for (int i = 0; i < n; ++i) {
        Z h = 0;
        for (int j = 0; j < m; ++j) {
            h = h * B + (a[i][j] - 'a');
        }
        for (int j = 0; j < m; ++j) {
            if (mp.count(h.val())) {
                dsu.merge(mp[h.val()], i);
                break;
            }
            h = (h - (a[i][j] - 'a') * x) * B + (a[i][j] - 'a');
        }
        if (dsu.find(i) == i) {
            mp[h.val()] = i;
        }
    }

    int q;
    std::cin >> q;
    while (q--) {
        int x, y;
        std::cin >> x >> y;
        --x, --y;
        if (dsu.same(x, y)) {
            std::cout << "Yes\n";
        } else {
            std::cout << "No\n";
        }
    }
}

int main() {
    std::cin.tie(nullptr)->sync_with_stdio(false);

    int t;
    std::cin >> t;

    while (t--) {
        solve();
    }

    return 0;
}