Output is now six time what it was before 1990.这里的what是什么意思?

问题描述:

Output is now six time what it was before 1990.这里的what是什么意思?

what在这里做双重身份,既做Output is now six time的宾语,也做 it was before 1990的宾语
现在的产量是1990年前的六倍

what引指后边整个后半句
输出是以前的6倍
what在这里代指以前的输出情况

输出(出口)现在是1990年以前的6倍.
句子有错误,应该是:
Output is now six times of what it was before 1990.
what在句中起引导从句的作用.