文中共有10处语言错误，每句中最多两处。错误涉及一个单词的增加、删除或修改。

增加：在此处加一个漏字符号（∧），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：在错的词下划一个横线，并在其下面写出修改后的词。

注意：1．每处错误及其修改均仅限一词；

2．只允许修改10处，多者（从十一处起）不计分。

All of us know the old saying “Practice make perfect．” It tells us unless we want to realize our aim, we should practise, and one day we will make it．It’s easy to understand．Once I wanted to learn swimming．At first I found difficult to control my body．I just sank into the water．I feel very frightened．Then I watched others who were good at them and asked them the key to succeed．I went to the swimming pool every day, learned from them and practised．A day, when my friend pushed me into the swimming poo1, I sudden found that I could swim．How exciting I was! Now I can swim much more better than before．

遗传和变异是生物界的普遍现象，现运用你所学的有关知识回答下列遗传和变异相关问题：

某植物（2N=24）的正常植株（A）对矮生植株(a)为显性。

假设两种纯合突变体M和N都是由控制株高的A基因突变产生的，检测突变基因转录的mRNA，发现M第二个密码子中的第二个碱基由C变为U，N在第二个密码子的第二个碱基前多了一个U。与正常植株相比，（）突变体的株高变化更大，因为（）。