（选修3-3选做题）
冬天到了，很多人用热水袋取暖。现有一中号热水袋，容积为1000cm3，正常使用时，装水量为80%，请估算该热水袋中水分子的数目约为多少个？（计算结果保留1位有效数字，已知1mol水的质量为18g，水的密度取1.0×103kg/m3，阿伏加德罗常数取6×1023mol-1）
解：热水袋内水的物质的量为
热水袋内水分子数为
带入数值得
个
Directions: Read the following passage．Fill in the numbered blanks by using the information from the passage．Write NO MORE THAN THREE WORDS for each answer． In a society such as the United States or Canada, which has many national, religious and cultural differences, people highly value individualism—the differences among people. Teachers place a lot of importance on the qualities that make each student special. The educational systems in these countries show these values. Students do not memorize information. Instead, they work on their own and find answers themselves. There is often a discussion in the classroom. At an early age, students learn to form their own ideas and opinions. In most Asian societies, by contrast, people have the same language, history and culture. Perhaps for this reason, the educational system in these Asian countries reflects society’s belief in group goals and purposes rather than individualism. Children in China, Japan and Korea often work together and help one another on assignments. There are advantages and disadvantages to both of these systems of education. For example, one advantage of the system in Japan is that students there learn much more maths and science than American students learn by the end of high school. They also study more hours each day and more days each year than North Americans do. The system is difficult, but it prepares students for a society that values discipline and self-control. There is, however, a disadvantage. Memorization is an important learning method in Japanese schools, but many students say that after an exam, they forget much of the information they have memorized. The advantage of educational system in North America, on the other hand, is that students learn to think for themselves. The system prepares them for a society that values creative ideas. There is, however, a disadvantage. When students graduate from high school, they haven’t memorized as much basic rules as students in other countries have. Title: A comparison of two different educational systems
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