import java.util.; import java.text.; import java.math.; import java.util.regex.;

public class Solution { static String morganAndString(String a, String b) { // Complete this function int lenA = a.length(), lenB = b.length(); StringBuilder sb = new StringBuilder(); int pA = 0, pB = 0; while (pA < lenA && pB < lenB) { if (a.charAt(pA) < b.charAt(pB)) { sb.append(a.charAt(pA++)); }else if (a.charAt(pA) > b.charAt(pB)) { sb.append(b.charAt(pB++)); }else { if (compare(a, pA + 1, b, pB + 1)) { sb.append(a.charAt(pA++)); while (pA < a.length() && a.charAt(pA) == a.charAt(pA - 1)) { sb.append(a.charAt(pA++)); } } else { sb.append(b.charAt(pB++)); while (pB < b.length() && b.charAt(pB) == b.charAt(pB - 1)) { sb.append(b.charAt(pB++)); } } } }

    if (pA < lenA) {
        sb.append(a.substring(pA));
    }

    if (pB < lenB) {
        sb.append(b.substring(pB));
    }

    return sb.toString();
}

private static boolean compare(String a, int i, String b, int j) {
    while (i < a.length() && j < b.length()) {
        if (a.charAt(i) < b.charAt(j)) return true;
        else if (a.charAt(i) > b.charAt(j)) return false;
        i++;
        j++;
    }

    return i == a.length() ? false : true;
}

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int t = in.nextInt();
    for(int a0 = 0; a0 < t; a0++){
        String a = in.next();
        String b = in.next();
        String result = morganAndString(a, b);
        System.out.println(result);
    }
    in.close();
}

}