The output of the wheat in Chongming County is three times__it was a decade

C
times 后面直接加名词的，如果是接句子就用that.

The output of the wheat in Chongming County is three times than it was a decade
小麦的产量,在县政府三倍是10
The output of the wheat in Chongming County is three times as it was a decade
小麦的产量在县政府的三倍,因为它是一个十年之久
The output of the wheat in Chongming County is three times that it was a decade
小麦的产量在县政府的三倍,它是一个十年之久
The output of the wheat in Chongming County is three times what it was a decade
小麦的产量是三次在县政府是什么有十年之久