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();
    }
}