听力原文：M: Did you hear about the air crash that occurred in South America recently? It was quite a tragic accident! W: No, I didn't see anything in the news about it. What happened? M: A foreign airliner was attempting to land at night in a mountainous area in Argentina and flew into a hill! W: That sounds really terrible! Did anyone survive? M: No, everyone aboard, including the crew, was killed instantly. W: What were the circumstances? Were they bad weather, a fire, or engine failure? M: Apparently, there were some low clouds in the area, but mostly it was just miscommunication between the pilots and the air traffic controllers. W: Weren't they both speaking in English, the official international aviation language? M: Yes they were, but the transition from poor quality radios was slightly distorted and the accents of the Spanish speaking controllers was so strong that the pilots misunderstood a vital instruction. W: How could a misunderstanding like that cause such a serious accident? M: The pilots were told to descend to 22, 000 feet. The instruction actually meant22, 000 feet, but they thought they heard descend 2, 000 feet. That's a huge difference, and it should have been confirmed, but it was not. Unfortunately, the terrain of the mountains in Norweija ascend to 2, 000 feet. W: So the pilots did descend to the wrong altitude then, because they were following the air controller's instructions. M: Sadly enough, yes they did. It was a really bad mistake. Many people died as a result of the simply misunderstanding. W: Wow, that's a powerful lesson on how important it can be to accurately communicate with each other. What was the cause of the tragedy?