1. food safety: in big cities, food safety is a very important issue. Many people may choose to buy food in supermarkets, but not all supermarkets can guarantee food safety. Therefore, it is suggested that when buying food, choose a reputable merchant or brand, or choose to cook by yourself.

2. Traffic congestion: Traffic congestion in big cities is a common problem. During rush hours, many people may choose public transportation, but public transportation may also be congested. Therefore, it is suggested to plan the travel route in advance, avoid the rush hour, or choose * * * to enjoy bicycles and other means of transportation.

3. Air pollution: Air pollution in big cities is also a common problem. When air pollution is serious, it is suggested to reduce outdoor activities or wear masks and other protective measures.

4. Garbage classification: In big cities, garbage classification is a very important issue. Many cities have begun to implement garbage sorting systems, but not all residents can correctly sort garbage. Therefore, it is recommended to understand the local garbage classification system and correctly classify garbage.

5. Social stress: In big cities, social stress is also a common problem. Many people may feel lonely or anxious, so it is suggested to actively participate in social activities and expand their social circle.

Generally speaking, there are many details of life in big cities that need our attention and attention. Only by dealing with these problems correctly can we better adapt to the life in big cities.