例句:Global warming is a real problem.
全球变暖是个严重的问题。

2.climate change 气候变化

例句:Carbon emissions exacerbate the global climate change problem.
碳排放加剧了全球气候变化问题。

3.bring down 降低

例句:You bring down the lion.
你把狮子给拉下来了。

4.renewable energy 可再生能源

例句:Renewable energy will become progressively more important as time goes on.
随着时间的推移，可再生能源将变得愈发重要。