6. Life in the countryside isn't as stressful as life in the city. (more)
Life in the city is more stressful than . Life in the countryside
7. It is quite easy to find a shopping centre in the city, but it is not easy to find one in the countryside. (than)
→Finding...a shopping centre in the city is easier than  finding  one in the countryside.
 8 I spent two hours doing this task and three hours doing that one. (than)
→ That task.......is longer than this one