When he was running after his brother, the boy lost his ___ and had a bad fall.

下列说法正确的是(   )

如图，在边长为12的正方形ABCD中，有一个小正方形EFGH，其中E、F分别在AB、BC上，FG在Rt△DCF上，若BF=3，则BE的长为（　　）

有一条小船停靠在湖边码头，小船又窄又长，一位同学想用一个卷尺粗略测定它的质量．他进行了如下操作：首先将船平行于码头自由停泊，轻轻从船尾上船，走到船头停下，而后轻轻下船．用卷尺测出船后退的距离为0.5m，然后用卷尺测出船长3m．已知他的自身质量为50kg，则渔船的质量约为（   ）

增加：在缺词处加一个漏字符号（∧），并在此符号下面写出该加的词。

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'm Li Hua , a student from FenDou Middle School, that has a history of 75 years. Lie in the west of ShanBa, it has seen great changes of this old town. I am proud to tell you that I studied hard since I came here. So far, under the help of my teachers and classmates I have learned lots of knowledges. Although I still have some trouble with maths at present, I won't lose my heart. I consider it not very difficulty to learn it well as long as I devote myself to learn it. I strong believe that I can be admitted by a key university.