下图表示一个动物细胞内外不同离子的相对浓度，由图分析可知维持细胞内外浓度依靠                  （    ）

阅读理解

In 1901, an Austrian scientist discovered that there are four types of blood. He named them A、B、AB and O. People have one of these four types. Blood type O is the most common around the world. Blood type A is the second most common, and blood type AB is the least common.

    In 1927, a Japanese doctor found that people with different blood types have different personalities (性格)，too. He said that people with type A blood are usually calm and serious; people with type B blood are cheerful and outgoing; people with type O blood are generous and honest; while those with type AB blood are often caring and talented.

    More recently, a doctor in the United States wrote a book that connects blood types with what people eat. The book suggests people with type O blood should eat more meat and less bread. A diet for people with type A blood includes more vegetables. His book, Eat Right for Your Type, has been a hit with people who want to lose weight. However, Dr. Peter D' Adamo believes that eating food that matches a person's blood type will make the person healthier in other ways, too.

（第四空三词，其余各题均两词）

为了解今年某校高三毕业班准备报考飞行员学生的体重情况，将所得的数据整理后，画出了频率分布直方图（如图），已知图中从左到右的前3个小组的频率之比为1：2：3，其中第2小组的频数为12．

（Ⅰ）求该校报考飞行员的总人数；

（Ⅱ）以这所学校的样本数据来估计全省的总体数据，若从全省报考飞行员的同学中（人数很多）任选三人，设X表示体重超过60公斤的学生人数，求X的分布列和数学期望．

选词填空 选择适当的词并用正确的形式填空，每词限用一次。  

                                                                                    Easy to say and hard to do

    There is ____ old man in a house. In the house there are many mice(老鼠). The old man ____ a cat. Every day the cat catches the mice and eats ____.

    One day, the old mouse says, “All mice must come to my room this evening. We must find a way to do with the cat.”

    All the mice come. Many mice speak, ____ they don't know what ____. At last, a young mouse ____ and says, “We must put a bell(铃铛) on the cat. When the cat comes ____,we can ____ the bell and run away. ____ the cat can't catch us.” “Who can put the bell on the cat?” asks the old mouse. But no one ____.