double L stair

例句：

1. 1. Theprice of the product has doubled sincelast year.
   该产品的价格自去年以来翻了一番。
2. 2. They doubled their efforts to finishthe project on time.
   他们加倍努力，按时完成这个项目。
3. 3. The company doubled itsprofits in the past year.
   该公司去年的利润翻了一番。