在纪念中国人民抗日战争暨世界反法西斯战争胜利70周年阅兵式上，******宣布裁军30万，显现了我国对局势的把控，对未来的自信。由此可见（   ）

如图所示，水平放置的平行金属导轨，相距l=0.50m，左端接一电阻R=0.20Ω，磁感应强度B=0.40T的匀强磁场方向垂直于导轨平面，导体棒ac垂直放在导轨上，并能无摩擦地沿导轨滑动，导轨和导体棒的电阻均可忽略不计，当ac以v=4.0m/s的速度水平向右匀速滑动时，求：

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。每处错误仅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（Λ），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。

    I have learned English for many years, but I don't have a real chance speak before foreigners. Last week, I happened to meet the foreigner. He badly needed my help and I felt so exciting. On Monday, I went to the flowers shop to buy a flower for my friend Mary, because she was ill. I was going to the hospital to see him. In the shop a foreigner and the boss was having a conversation, so the boss didn't know what the foreigner said. I hesitate for a while, then I came to help the boss. The boss and the foreigner thanked for me so much. I felt so happy though the language I learn is useful. Since then, I have been determined to learn English well.