阅读图文资料，完成下列问题。

材料一：左为欧洲区域图（局部），S半岛为该区域最大的半岛，右为某日m地的太阳高度日变化示意图。

材料二：芬兰湾以北陆域几乎没有地震、火山、滑坡、泥石流等地质灾害，森林覆盖率为75．3%，林间野生动植物种类繁多，拉普兰地区是当地主要的驯鹿牧区，人口密度约为2人/平方千米，近两百多年来驯鹿牧区范围变化不大。

阅读理解

    When I was five years old. I took a boat out on the river and went fishing by myself. I really wanted to catch a fish! But they were not biting.

    I stayed in my boat for three days, waiting. A few times, I thought I felt a fish at the end of the line. The first time I pulled in my catch, it was not a fish; it was an old bag. The second time, it was a shoe. Finally, at the end of the third day, I felt a strong pull at the end of the line. The pull was so strong they my boat raced around and around. I needed all my power just to hold onto the fishing rod. I pulled, and I pulled and I caught the biggest fish that ever swam on the Earth! It was heavier than everyone in this room put together! Then something terrible happened!

    After I pulled the huge fish into my boat, I saw that the boat was going under water! Water was coming into the boat from all sides! I was not a very good swimmer, so I was scared.

    Although it was the hardest choice I ever made. I had to let the fish go. I pushed it back over the side of the boat, and we waved good-bye to each other as it swam away.

Na₂O₂具有强氧化性，H₂具有还原性，某同学根据氧化还原反应的知识推测Na₂O₂与H₂能发生反应。为了验证此推测结果，该同学设计并进行如下实验。

I.实验探究

步骤1：按如图所示的装置组装仪器（图中夹持仪器已省略）并检查装置的气密性，然后装入药品。

步骤2：打开K₁、K₂，在产生的氢气流经装有Na₂O₂的硬质玻璃管的过程中，未观察到明显现象。

步骤3：进行必要的实验操作，淡黄色的粉末慢慢变成白色固体，无水硫酸铜未变蓝色。

阅读下面这首唐诗，完成后面题目。
                                                                                          春远
                                                                                         唐  杜甫
                                                       肃肃^①花絮晚，菲菲^②红素轻。日长惟鸟雀，春远独柴荆。
                                                       数有关中乱，何曾剑外清。故乡归不得，地入亚夫营^③。
注释：此诗是永泰元年春杜甫在浣花溪作 ①肃肃，花落的声音。②菲菲，花落的样子。③亚夫营，指戒备森严的军营。

在“菊花的组织培养”、“多聚酶链式反应扩增DNA片段”等实验操作中均需注意的问题之一是：注意保持材料用具等的无菌．这里所说的“菌”实指（   ）