阅读短文，然后用短文括号中所给词的适当形式填空。
Believe it or not: the more TV you watch, the 78 (little) happiness you get. This is the result of a new study. It shows that unhappy people watch more TV than happy people.
Well, you may say that you enjoy 79 (watch ) TV. In fact, TV gives you happiness for a short time, but unhappiness for a long time.
Why? It is because, if you watch TV, you cannot take part in many other good 80 (activity). And sometimes, if you are unhappy, you 81 (usual) prefer being a couch potato(整天坐在沙发上看电视的人)，right? Watching TV is relaxing to you.
Then if you want to be happy, what should you do? You can read newspapers, visit 82 (you) friends, go to parties, … but don’t watch television all the time. Now turn off the TV, and take a walk outside. It’s the 83 (one) step to being happy!
xC（g）+ 2D（g）△H<0。2min末该反应达到平衡，生成0.8mol D ，并测得C的浓度为0.2mol·L－1。请填空：