a couple of 后面加可数名词复数
people是单复数同型的.类似sheep.
通常a couple of后面用复数名词,它的意思相当于a few.a couple of days的意思相当a few days.这类词组作主语时,谓语动词常用复数形式,例如：A couple of/ a few days have passed.但用于there be的句型时,因为习惯上要遵循就近一致的原则,所以一般用单数的动词形式,例如：There is a couple of vacant rooms behind the office.
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