五．短文改错。（共10分）（注意：答案写在答卷上，注意规范）。

文中共有10处语言错误。错误涉及一个单词的增加、删除或修改。

增加：在缺词处加上一个漏字符号（∧），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仅限一词。

2．只允许修改10处，多者（从第11处起）不记分。

Miss Evans taught physics in school in London．Last month she was explaining to one of her class about sound ，and she decide to test them to see what successful she had been in her work．She said to them， “Now I has a sister in Washington． If I called her by the phone， and you were on the other side of the street． Who would hear me first， my sister and you？ And why？” A clever boy at once answered， “You sister， Miss Evans， because the electricity travels much faster than sound waves．” “Very well，” Miss Evans praised．

（8分）用200 mL  1 mol/L 氯化铝溶液与一定量 3 mol/L的氢氧化钠溶液混合，可得到氢氧化铝7.8g，请计算需要此氢氧化钠溶液的体积为多少毫升？（写计算步骤）