a recent national study of the public schools showsA recent national study of the public schools shows that there is now one microcomputer for every thirty-two pupils,four times as many as there (were) four years ago请问这里there后为什么是were哦?

问题描述:

a recent national study of the public schools shows
A recent national study of the public schools shows that there is now one microcomputer for every thirty-two pupils,four times as many as there (were) four years ago
请问这里there后为什么是were哦?