flag=0
lst = []
num = int(input(""))
for i in range(0,num):
temp = input("")
#lst.insert(i,temp)
for j in range(0,len(temp),2):
if temp[j] == temp[j+1]:
flag=1
break;
if flag == 1:
#print("no")
lst.insert(i,"no")
else:
#print("yes")
lst.insert(i,"yes")
for i in lst:
print(i