A. to invent

　　B. inventing

　　C. to have invented

　　D. having invented

　　Suggested answers:

　　1. D　2. B　3. C

　　→ Step 2 Listening and Vocabulary

　　1. In the following section we will learn some new words and then we will listen to a short dialogue.

　　First look at the words in the box and read after me. Pay attention to the words where the stress is not on the first syllable: dioxide, environment, pollution.

　　Then ask students to match the words with the definitions individually.

　　Then check with their partners.

　　After that, ask back the answers in a whole class setting, having one student read the definition and another provide the word.

　　If possible, ask more groups to do that.

　　atmosphere

　　carbon dioxide

　　chemical

　　damage

　　environment

　　garbage

　　melt

　　pollution

　　recycle

　　the Poles 　　1. the air around the earth

　　2. to have a bad effect on someone or something

　　3. a substance used in chemistry

　　4. the natural world-the land, air, water, plants and animals

　　5. to change from solid to liquid, e. g. ice becomes water

　　6. to treat something so that we can use again

　　7. one of the gases in the air

　　8. the most northern and southern points on earth

　　9. rubbish

　　10. damage to the environment because of chemicals

　　Suggested answers:

　　1. atmosphere　2. damage　3. chemical　4. environment　5. melt　6. recycle　7. carbon dioxide　8. the Poles　9. garbage　10. pollution

　　2. Listen to an environmental expert's speech. Put the topics below in the order you hear them.

　　First, read through the list of topics.

　　Second, play the tape once while students just listen. Then play it again for them to rank the topics.

　　Third, play it once more for them to check their answers.

　　A. garbage　B. trees　C. pollution　D. melting ice at the Poles　E. the climate

　　Suggested answers:

　　1. E　2. D　3. C　4. B　5. A

　　3. Have a quick look at the words and questions in Activity 3.

　　After that, play the tape twice for students to answer the questions.

　　Then, play again for them to check their answers.

　　1 What is the most urgent problem of all?

　　2 What examples of coastal cities does David give?

　　3 Why is the climate getting warmer?

　　4 What is described as a major problem?

　　5 What happens when we cut down a lot of trees?

6 How does the interviewer feel about the situation?