1. This app allows you to review lessons by playing games

2. We were cleaning up the beach when it started to rain

3. Ecotourism provides tourists with opportunities to explore nature

One of the most serious environmental problems in Vietnam today is air pollution. In big cities like Hanoi and Ho Chi Minh City, the air quality is often very poor due to traffic congestion, industrial emissions, and construction dust. This problem not only affects the environment but also causes serious health issues such as asthma, lung cancer, and other respiratory diseases. To solve this problem, the government should strengthen environmental regulations and limit the number of vehicles on the road. People should be encouraged to use public transportation, ride bicycles, or walk more often. In addition, factories should be required to install air filters and reduce their harmful emissions. Raising awareness in the community through campaigns and education is also necessary. In conclusion, air pollution is a major issue that needs immediate attention. With cooperation from both the government and citizens, we can improve the air quality and protect our health and environment