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U2 More Practice

发布时间:2013-11-02 08:05:45  

Warming up

数字的产生
人类最早用来计数的工具是手指和脚趾, 但它们只能表示20以内的数字。当数目很多时, 大多数的原始人就用小石子和豆粒来记数。渐 渐地人们不满足粒为单位的记数,又发明了打 绳结、刻画记数的方法,在兽皮、兽骨、树木、 石头上刻画记数。中国古代是用木、竹或骨头 制成的小棍来记数,称为算筹。这些记数方法 和记数符号慢慢转变成了最早的数字符号(数 码)。如今,世界各国都使用阿拉伯数字为标 准数字。

阿拉伯数字的来源
数字并不是阿拉伯人发明创造的,而是发 源于古印度。数字后来被阿拉伯人用于经商而 掌握,经改进,并传到了西方。西方人由于首 先接触到阿拉伯人使用过这些数据,便误以为 是他们发明的,所以便将这些数字称为阿拉伯 数字,造成了这一历史的误会。后来,随着在 世界各地的普遍传播,大家都认同了“阿拉伯 数字”这个说法,使世界上很多地方的人都误 认为是阿拉伯人发明的数字,实际上是阿拉伯 人最早开始广泛使用数字,尽管后来人们知道 了事情的真相,但由于习惯了,就一直没有改 正过来。

数字的表示方法
数字是一种用来表示数的书写符号。 不同的记数系统可以使用相同的数字,比如, 十进制和二进制都会用到数字“0”和“1”。 同一个数在不同的记数系统中有不同的表示, 比如,数37(阿拉伯数字十进制)可以有多种 写法: 中文数字写作三十七 罗马数字写作XXXVII 阿拉伯数字二进制写作100101

While-reading
A Read the online article and then complete the flow chart about the development of counting methods.

First, people used(1)_____________________________________________. used their fingers, and even their toes. After that, they made(2)_________________________________________. small marks on sticks and bones. tokens made from clay or small stones. Then they used(3)________________________________________________. Finally, they began to develop(4)_______________________________. systems of written marks This led to (5)____________________________________________________. the Hindu-Arabic system(0-9)
B Are there any other ways of counting? Discuss this with your classmates.

Counting before numbers
Before the invention of written numbers, people used many different ways to count things. At first, people used their fingers, and even their toes. However, they could only count small numbers in this way. After that, they began to make small marks on sticks and bones. This helped them count bigger numbers. They used them to count things like the days of the month, the amount of food and the number of animals they had. Then people began to use tokens made from clay or small stones. This helped them count even bigger numbers. They often put the tokens on pieces

of string so that they could carry them around easily. This developed into tools like the abacus. Finally, people began to develop systems of written marks to show different numbers, and this led to the Hindu-Arabic system(0-9). We are still using this system today.

Language points
1. They used them to count things like the days of the month, the amount of food and the number of animals they had.(L7)

the amount of /the number of +名词,谓语用单数, 因为主语仍是“数量” an amount of +不可数名词,谓语用单数 a number of +可数名词复数,谓语用复数
1.降雨量决定着收成的好坏. The ____________ of ________ amount _____ rainfall determines the quality of the crop. 2.百万美元是一笔庞大的资金. an amount of A billion dollars is _____ __________ ______ money. 3.我访问了亚洲的许多科学协会. a ___________ _____ I visited _____number of scientific institutes in Asia. 4.这所学校的学生人数在减少. The number of ______ ___________ ______ students of this school has shrunk.

Important Phrases

关于…的发明
首先 接着 然后 最后

the invention of

at first
after that

then
finally lead to

导致


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