用量词a pair of，a pair of scissors为固定搭配，中文意思是，一把剪刀，一副剪刀

例如

While you're at it， you could cut your grass with a pair of scissors and wash your car with an old toothbrush.

当您做到这一点后，您可以用剪刀剪草，用旧牙刷洗车。

That's not the right way to hold a pair of scissors.