当couple做“（夫妇）两个人”解时,它的谓语动词应当使用复数：
The couple were sitting just behind me.
这对夫妇就坐在我的后面.
当couple表示若干对中的一对,即表示一个单位时,其谓语动词应该用单数：
1) Each couple was asked to complete a form.
要求每对夫妇填一张表.
2) And tonight's winning couple is George and Dorothy Lightfoot.
今晚获胜的一对是乔治和多萝西.莱特福特.
参考：
couple表示“夫妇”“夫妻”且用作主语时,谓语动词可用单数（视为整体,尤其是当有each, every, only one等修饰时）或复数（考虑其个体）.如：
The couple were married last week. 这一对夫妇是上星期结的婚.
Each couple was asked to complete a form. 要求每对夫妇填一张表.
有时语境上不明确强调个体还是整体,则用单数或复数均可：
The couple is [are] spending its [their] honeymoon. 这对新婚夫妻在度蜜月.
另外,couple还可表示“一些”“几个”,此时表示复数意义,用作主语时,谓语动词要用复数.如：
我的几个朋友准备开办一个旅行社.
误：A couple of my friends is going to open a travel agency.
正：A couple of my friends are going to open a travel agency.
希望对你有所帮助,学习愉快……