下图中左图示意我国南极四个考察站分布，右图是泰山站主楼照片。完成下列各题。

如图，AD、BC是⊙O的两条互相垂直的直径，点P从点O出发，沿O→C→D→O的路线匀速运动．设∠APB=y（单位：度），那么y与点P运动的时间x（单位：秒）的关系图是（   ）

电视已经走进了千家万户，是我们生活的重要组成部分。每个人都有自己最喜爱的电视节目。下面是五个人的描述，请根据他们的描述从A-F中为他们选择合适的电视节目。
____ I am 73 years old. I often watch TV in my free time. Of all the programs, I like the news best. Through the TV, I can learn what is happening in our country and in the world. At seven every evening , I always sit in front of the TV.
____ I am a grandma. I like Chinese traditional opera. From Monday to Thursday, I usually turn on the TV at half past seven. The programs from CCTV7 are my best.
____ I am a basketball fan. I like playing basketball very much. But I am too busy. So I have to watch it on the TV. Every night, I watch the match till midnight.I am crazy about it , especially NBA
____ I am a housewife. I do the housework all day, I’d like to watch TV at night. I prefer to see soap operas like ‘palace”, “meteoric garden” and so on.Because they can make me feel relaxed.
____ I am the only son in the family. I am in Grade Five. I like cartoons best. I often watch cartoons on the TV after doing the homework.
 
A   B
 
C                         D                     
 
E                         F.

阅读课文《绿叶的梦》选段，回答问题

      我永远感激我的启蒙老师。除了教我们读书以外，老师还教我们搜集标本，采来各种绿叶汇拢在一起，并讲述它们的知识和趣闻。那真是令人愉快的活动。

收集标本在文中起到了什么作用？