q = int(input())

for test_case in range(q):
    n = int(input())
    cnt = 0
    val_s =[]
    for i in range(n):
        val = [int(ele) for ele in input().split()]
        val_s.append(val[0])
        val_s.append(val[1])
    max_outer = max(val_s)
    for co_idx in range(0,len(val_s),2):
        if val_s[co_idx] == 0 or val_s[co_idx+1] == 0:
            cnt+=1
        elif (val_s[co_idx] == val_s[co_idx+1]):
            if (val_s[co_idx] < max_outer or val[co_idx+1] < max_outer):
                cnt-=1
            else:
                cnt+=1
    #print(cnt)
    if cnt == len(val_s)/2:
        print ("YES")
    else:
        print ("NO")