A proverb says :"Time is money."But in my opinion, time is even more valuable than money. Why? Because when money is spent ,we can earn it back .However when time is gone ,it will never return .This is the reason why we must value time. There is no doubt that the time we have is unusually limited. So even an hour is extremely precious. We should make full use of our time to do useful things .As students we must not relax our efforts to engage in our studies so as to serve our society and our nation in the future. But it is pity that there are a lot of people who do not know the importance of time .They spend their valuable time smoking, drinking and so on. They do not realize that wasting time is equal to wasting a part of their valuable life. In a word, we should get into a good habit of saving time. Do not put off what can be done today until tomorrow. Laziness will not only bring us failure but also lead us to the road of poverty. People who spend time smoking, drinking   _  .
do not know how to kill time as clearly as others doubt that they will become more dangerous to society realize how important their lives are waste their whole lives without realizing the importance of time