完形填空

　　We are often warned by our teachers not to waste time because time 1 will never return. I think it quite 2 . What does time look 3 ? Nobody knows, and we can't see it or touch it and no amount of money can buy it. Time is abstract, so we have to 4 it.

　　Time passes very quickly. 5 students say they don't have 6 time to review their lessons. It is 7 they don't know how to make 8 of their time. They waste it in going to theaters or parks, and 9 other useless things. Why do we study every day? Why do we work? Why do most people have to take buses instead of walking? The answer is very 10 . We wish to save time because time is priceless.

　　Today we are 11 in the twenty-first century. We 12 time as life. When a person dies, his life ends. Since life is short, we must 13 our time and energy to study so that we may be able to serve the people well in the future . laziness is the 14 of time, far it not only brings us 15 , but also does other 16 to us. If it is 17 for us to do our work today, 18 us do it today and not 19 it until tomorrow. Remember that time is much more 20 .

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