Clean the Air

• 来源期刊: 空中英语教室:初级版.大家说英语
• 学科: 工学
• 关键词: problems. CLEAN SPEND
• 年，卷（期）: 2021,（2）
• 页码范围: 24-25
• 页数: 2页
• 分类号: TS9

摘要

Everyone likes to breathe clean air.Bad air or air pollution can cause sleep and allergy problems.Indoor air is two to five times more polluted than outside air.And many people spend 90 percent of their time inside.An air purifier can help keep air clean.Some purifiers are large and can clean the air in an entire room.Others are small.