某人以八折优惠价买一套服装省了25元，那么买这套服装实际用了（　　）

美国内战前和俄国1861年改革前资本主义经济发展所面临的共同障碍是（     ）

如图所示是小明用天平称测量某物质的质量，其读数为____ 

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。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）每处错误及其修改仅限一词；

2）只允许修改10处，多者（从第11处起）不计分。

    Though English is a hard subject, but I like my English teacher a lot, and so are my classmates. She is nice to us and always tells us stories of the days when she was in her twenty. Sometimes she even stayed in school to help students make up for their lessons. She always encourages us and tells us do our best. We are gratefully to her, so one day we bought him a cake and a gift. We also made a big card for her, on it we wrote all our names. Seeing these, she was moving and had a big smile in her face.