a couple of 的作用和pair是一样的，只是表达成双或者数量上的问题，假如是个整体即2个一组应该是按单数计算，实际上意思也和few 相近，比如：A couple of minutes are not enough. 另外单独把couple拿出来看作是一对夫妇，用单数还是复数也要看具体的情况： The couple were married last week. Only one couple was unaccounted for. 希望能帮助你。

  应该是复数， a couple of =two

  应用复数