Your translation is very good! However, there are just some parts where you'll have to take note, such as the important use of 'the' in some of the sentences and the clauses have to be separated properly. As in, different parts of one sentence which can be separated into two sentences, have to be separated. Also, if this essay were to be expository, contractions, such as can't instead of cannot, don't instead of do not, should not be used. Otherwise, it's a SUPER job! 时间很重要。人人每天有24小时，每年有365天，一旦我们生命中的一天消逝，就再也不会回来。我们要是热爱生命，就不应该浪费时间。我们应该掌握时间。使用时间的最好办法就是好好计划时间。 在制定学习计划时，我们应该记住两件事。第一，应该现实一些，不要企图干太多的事情。第二，好的计划要灵活一点。我们可以每周做些小的变动，但总的模式不变。让我们当时间的主人，今天就开始我们的计划。 Time is important. everybody has twenty-four hours each day and three hundred and sixty five days each year, once a day of our life has gone, it won’t back again. If we (are to) enjoy life, we shouldn’t waste time. We should control time. The best way to use time is plan time well. We should remember two things when plan study time. The first, be realistic, don’t (plan) to do too many things. The second, a good plan must be a little flexible. We can make (it with <cancel out>) a (little <cancel out>) few changes per (instead of each) week, but don’t upset (the) entire plan. Let’s be the master of time and start our plan today.

No. I don't mind about anything. I am ready to do your exercise

Oh! What a answer which you give yourself . I am very impress with you. In my openion nobody sentence is wrong in your answer but it is a exellent answer.