短文改错。
假定英语课上老师要求同桌之间交换修改作文,请你修改你同学写的以下作文。文中共有10
处语言错误,每句中最多有两处。错误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仅限一词;
2．只允许修改10处,多者（从第11处起）不计分。
Now paper still come from trees. Unfortunately, we use a lot of paper every day. We mustn't waste paper,
or there will not have any trees leaving on the earth. No trees means no paper. We need 17 trees make one ton
of paper. We must start using fewer paper. How can we save paper? Firstly, we can use both sides of paper.
We can reuse again envelopes. We can use plastic cups and plates instead of paper one. We can either use
handkerchiefs instead of paper tissues. Beside, we can use fewer paper shopping bags and we can reuse these
paper bags late.
_________________________________________________________________________________________
nC(g) +2D(g),经过5min后，测得D的浓度为0.5mol/L，c(A):c(B)=3:5,C的平均反应速率为0.1mol/(L.min).