第一单元

Unit one

China's hot pole——Know the number

(中国的热极——认识数)

1. What is the meaning of 13 above zero and 3 below zero? How to express it?

零上13℃与零下3℃是什么意思？怎样表示？

2. We do this with the help of a thermometer.

我们借助温度计来研究。

3. I know the thermometer starts at zero degrees Celsius.

我知道温度计以0℃为分界线。

4. Above zero 13℃ above 0℃, minus 3℃ below 0℃.

零上13℃在0℃以上，零下3℃在0℃以下。

5. How do we record these two temperatures?

怎样记录这两个温度呢？

6. 13℃ above zero, which is expressed as "+13℃".

零上13℃，用“+13℃”表示。

7. 3℃ below zero, which is denoted by "-3℃".

零下3℃，用“-3℃”表示。

8. What does it mean to be 155.31 meters below sea level?

比海平面低155.31米是什么意思？怎样表示呢？

9.So how do we express that?

把海平面看成分界线，用“0”表示。

10. What does it mean to be 831.7 meters above sea level?

比海平面高831.7米是什么意思？

11.What is a positive number? What is a negative number?

什么是正数？什么是负数？

12. 0 is neither positive nor negative.

0既不是正数，也不是负数。

13. Can you find examples in your life where positive and negative numbers are used?

你能找一找生活中运用正、负数的例子吗？

14. Quantities having opposite meanings can be expressed as positive or negative numbers.

具有相反意义的量，可以用正、负数表示。