1， 第二句中：are opened for free.

2,it has a purpose ？ 此处最好用，There's a purpose 或者直接用状语从句：nowdays more and more museums are opened for free to attract the people ,especially the students to visit them ,which show the culture relics and the society's develop.

3.＂It is a beneficial activity.＂已经下结论？应该是 many people think .....

4 ,free admission have ？ 单复数

5，第三段第一句为废话

6,it will lead to the order in mess，中应为 lead the order in mass

7,the public environment is also a serious problem that a part of visitors always throw away the plastic bottles and papers everywhere能看出我哪里改动来了吗？

8 So many workers who work in the museums think that the museums shouldn't opened freely. 中 who work in 去掉，将后面的shoudn't 中的not 提前为，don't think that 后面为肯定句。

9 I think the museum should open freely ,but it can limit the quantity of people every day. BUT 改为AND can -MAY .

10 最后一句中，who 应该去掉，visiting 已经是后置定语。后面的museums去掉。

如果总分25分的话，可以得12分左右。 主题不清晰，是一大问题。