①我国国民受教育年限和发达国家相比有很大的差距

②我国人口基数大，人口增长快

③我国的人口分布不平衡

④与发达国家相比，我国的人口素质偏低

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（＼）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1).每处错误及其修改均限一词;

      2).只允许修改10处，多者（从第11处起）不计分。

    As the saying goes, time is money. But in my opinion, time is even precious than money. Why? Because when money is spent, we still have a chance to earn them back. But when time is wasting, we can never get it back. There is some doubt that time is very limited, and even a minute is of great valuable. We should make full use of time to do that should be done. It's the pity that a lot of people still didn't appreciate the value of time. They are wasting their time doing nothing of useful. We should form the good habit of race against time and make a difference in our world.

我们每个人都有不同的情感，情感的发展需要我们一生自身的努力和培训，而情感发展的关键时期是（      ）