增加：在缺词处加一个漏词符号(/\)，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： 在错的词下画一横线，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。

    As the saying goes, many little drop of water make an ocean. A small action may lead to major changes took place in society. My friends and I had participated in a voluntary activity at a nursing home last week. We first did some cleaning or washing. After that we spent half an hour chatted with the old people living there. Though it was a tired day, we were happy with that we did. I felt a sense of responsibility by visiting the old. If all of us lend a helping hand to the people in need, they can live in harmony with each other. A society is just as a family. If we are willing to help others, our small actions can make big difference.

将H₂、CO、CO₂、N₂依次通过足量下列物质：澄清石灰水、灼热的氧化铜、浓H₂SO₄（注：有吸水性），最终剩余的气体为（　　）

数列$\left\{a_n\right\}$中，$a_1=2,a_{n+1}=a_n+\frac{2}{n\left(n+1\right)}\left(n\in N^{*}\right)$则$a_{10}=$ (       )

如图，把一个小球垂直向上抛出，则下列描述该小球的运动速度v（单位：m/s）与运动时间（单位：s）关系的函数图象中，正确的是（   ）