hard still enable

例句：

1. 1. The road was hard to drive on at night.
   这条路在晚上开车很难。
2. 2. He worked hard to improve his English skills.
   他努力提高他的英语技能。
3. 3. The project is hard to complete due to the complexity of the task.
   由于任务的复杂性，这个项目很难完成。