t = int(input())
for _ in range(t):
    n = int(input())
    items = [input().split() for _ in range(n)]
    ans = True
    for i in range(n):
        if items[i][0] == "a":
            ans = False
    if ans:
        print("No")
        continue
    ans = False
    cnt = 0
    for i in range(n):
        if items[i][0] == "a":
            if items[i][1].count("a") == 0:
                cnt = max(cnt, len(items[i][1]))
            else:
                ans = True
    if ans:
        print("Yes")
        continue
    cnt2 = float("inf")
    for i in range(n):
        if len(items[i][0]) == items[i][0].count("b"):
            cnt2 = min(cnt2, len(items[i][0]))
    print("Yes" if cnt >= cnt2 else "No")