We each have a memory（记忆力）. That's why we can still remember things after a long time. Some people have very good memories and they can easily learn many things in a short time, but some people can only remember things when they say or do them again and again. Many of the great men of the world have got surprising memories.

    A good memory is a great help in learning a language. Everybody learns his mother language when he is a small child. He hears the sounds, remembers them and then he learns to speak. Some children are living with their parents in foreign countries. They can learn two languages as easily as one because they hear, remember and speak two languages every day. In school it is not so easy to learn a foreign language because the students have so little time for it, and they are busy with other subjects, too.

    But your memory will become better and better when you do more and more exercises.

—What       the number of the students in your class ?

—About 60 . A number of them       girls .

某生物兴趣小组的同学进行探究萘乙酸（NAA）促进插条生根最适浓度的预实验，结果如图1所示．在预实验的基础上，他们又进一步设计如下实验探究萘乙酸促进生根的最适浓度．

材料用具：生长旺盛的一年生月季枝条若干、烧杯、培养皿、量筒、NAA、蒸馏水等．

配制一系列具有浓度梯度的萘乙酸溶液5份，编号1～5．

实验步骤

第一步：将月季枝条随机均分为5等份；

第二步：将5份枝条的基部分别浸泡在1～5号NAA溶液中；

第三步：一天后，取出枝条分别进行扦插；

第四步：每天对扦插的枝条生根情况进行观察记录．

请回答相关问题．

阅读下列材料，回答问题

材料一：唐太宗在端门看见新进士鱼贯而出，高兴地说：“天下英雄，入吾彀中矣。”（本义为张满弩弓，引申为牢笼、圈套）

材料二：“虽在农与工肆之人，有能则举之。高予之爵，重予之禄，任之以事，……故官无常贵，而民无终贱。有能则举之，无能则下之。”

——《墨子》

下列四幅区域示意图中，比例尺最小的是（　　）