Teaching aims

Enable the students to master the usage of the form it is/was... that.....

Teaching important points

How to enable the students to know the structure and the usage of the form it is/was... that....

Teaching difficult points

How to help the students to master the usage of the form it is/was... that....

Teaching aids

tape recorder, slides

Teaching procedures

Step1 Revision

T: First let's check answers. (slide show)

Discovering useful words and expressions. (P28)

1. Charles Keeling collected ______on the carbon dioxide content in the atmosphere over a forty-year period. He found that the amount of carbon dioxide _______ increasing during that time.

2. Although we are burning coal in huge _________ every year, we won't ________ of it for centuries.

3. If the amount of greenhouse gases continues to _______ we could be facing a global __________.

4. Many scientists believe that global warming has __________ through the burning of fossil fuels. They do not think that ignoring the issue is worth the ____.

5. ______ describes weather conditions over a period of years in a particular place.

6. The _____________ of a rising sea level would be widespread flooding.

7. The use of energy in Susanna's country is low ______________ the use of energy in the USA.

8. The warming of the earth is a _____________ that causes great concern.

9. The ________ shows temperature changes during the 20th century.

10. One hectare of forest can absorb 23 tons of carbon dioxide ____ year.