backward class

例句：

1. 1. The team was struggling to catch up with the competition.
   球队正在努力赶上比赛。
2. 2. The old man had a hard time getting around in his back yard.
   这位老人在后院里行走很困难。
3. 3. The economy is still backward compared to the developed countries.
   与发达国家相比，经济仍然落后。