铌的折射率:the pair of shoes(was) worn out 对吗? why?

the pair of shoes(was) worn out 对吗? the pair of shoes(was) worn out 对吗? why? the pair of shoes (were) worn out 对吗? why? A man in the State of Zheng decided to buy himself a pair of shoes. I will buy a pair of shoes if the store ____(open) soon. the pair of shoes ( ) worn out？ A.was found B. was founded why？ 是a beautiful pair of shoes 对还是a pair of beautiful shoes对? this pair of shoes 是单数还是复数? A pair of shoes后面跟is还是R? the pair of用单还是双？？？？