解方程 x²+2x+1=4；

增加：在缺词处加一个漏字符号（∧），并在此符号下面写出该加的词。

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仅限一词；2.只允许修改10处，多者（从第11处起）不计分。

    Everyone needs help.Often there are some cases that we help ourselves indirect in helping others.Last month, Tom asked for me to help him with his math.In order to help him,I go over the textbook again and again,and did lots of exercises.To his surprise,some difficult problems that I could not understand before worked out by myself.After a month,with my help,Tom made great progresses in math,too.Such a experience enabled me to realize that help others also does good to ourselves.So when others is in trouble,never hesitate to help them.

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读课文《捞铁牛》第三自然段，写出怀丙和尚为捞铁牛做的准备工作： ____。