Put the following sentences in the order of Beginning, Build-up, Climax, and Ending. Air pollution is a serious problem. Cars and buses that run on gas make the air dirty, which 1. Leo and Mia found a locked box and opened it with the golden key. harms people’s health. To solve this, some countries use biofuel made from waste. In London, coffee waste is turned into biofuel for buses. Here’s how it works: 2. Leo saw a small path and followed it to a dark cave. 3. Leo and Mia gave the treasure to the village elder to help the people. 4. Leo found a golden key behind a stone door.

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