double elevator

例句：

1. 1.We need to double the number of workers to meet the demand.
   我们需要增加工人数量以满足需求。
2. 2. The company doubled its profits last quarter.
   该公司上个季度的利润翻了一番。
3. 3. They doubled back after dinner.
   晚饭后他们折返回来。