完型填空。阅读下面短文，掌握其大意，然后从以下题所给的A、B、C、D四个选项中，选出最佳选项。
Someone says, “Time is money.” But I think time is __1__ important than money. Why? Because when money is spent, we can get it back. However, when time is 2 it’ll never 3 . That’s 4 we mustn’t waste time.
It goes without saying that the 5 is usually limited. Even a second is very important. We should make full use of our time to do 6__ useful.
