3. Listen to the talk again. Choose the correct answers A, B, or C.

(Nghe nói chuyện một lần nữa. Chọn câu trả lời đúng A, B hoặc C)

1. The world’s biggest source of soot is ____________.

A. burning forests

B. burning crop waste

C. killing living things in the soil

2. Black carbon only stays in the atmosphere for a few ____________.

A. hours           B. days or weeks           C. months

3. Black carbon speeds up _______________.

A. the release of sunlight into the air

B. burning of crop waste

C. ice melting

4. The next part of the talk will probably be about ______________.

A. ways to reduce black carbon emissions

B. heat-trapping gases

C. other heat-trapping pollutants