We're studying subject after the verb.
1.(Has, Have) your neighbors moved to Phoenix yet?
2.There (is,are) fifty states in the United States.
3.(Is, Are) the loaves of bread in the oven?
4.(was, Were) your parents born in Sweden?
5.(Has, Have) Marie and Nina looked at the map?
1.Have
2.is
3.Are
4.Were
5.Have
All are correct except # 2.
The subject is "states."