阅读下列材料，在空白处填入适当的内容（一个单词）或括号内单词的正确形式。
A proverb says, “Time is money”. But in my opinion, time is even _______ precious than money. Why? _____ when money is spent, we can earn it back. However, when time is _______(go), it will never return.
_______ is known to all that the time we can use is limited. Therefore we should make_______ use of our time to study hard so as to serve our country in _____future.
But it is a pity that there are a lot of people_____  do not realize the value of time. They spend their precious time ______(play).
In a word, we should form the good habit of______(save) time. Do not put off what can be done today ______tomorrow.