LDD

例句：

1. 1. I've been looking for the lost dog for days, but I can't find it.
   我已经找了好几天，但找不到那只丢失的狗。
2. 2.The company's stock price has been declining recently.
   这家公司的股票价格最近一直在下降。
3. 3.The government has been trying to solve the problem of pollution for years.
   政府多年来一直在试图解决污染问题。