读北京地形示意图，北京及其周围地区的地势特点是（    ）。

增加：在缺词处加一个漏字符号( $\wedge$ )，并在其下面写出该加的词。

删除：把多余的词用(＼)划掉。

修改：在错的词下画一横线，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。

    As it is known to us, fewer and fewer students do sports regularly, what makes them weak and easily tiring. There are many reasons about  this. First of all, some of the students complained that they have too many homework, resulting in less time to take exercise. Beside, some of them think that it is very difficulty  for them to keep doing exercise, because it is a very hard thing. Because lack of physical activities, many students are in poorly health. I suggested that our school must take measures to encourage more students to take part in sports. For us students, no matter what busy we are, it is necessary to spare any time to do exercise.