some of the equipment in our lab ( ) introduced from shanghai,and the rest ( )bought in our city

题目

some of the equipment in our lab ( ) introduced from shanghai,and the rest ( )bought in our city
答案：was was 为什么都是单数?

答案

这是因为主语指的是“设备"(equipment)",此词在英语中是不可数名词,所以谓语用单数was
后面的The rest "其余的”指的也是equipment