Đề 4:

Dear Sir,
I wrote this email to talk about today's predictions of a city of the future. It is still our familiar city, but in the future, the city is no longer smog, because it has been equipped with smart air purifiers installed on street lights and traffic lights. In addition, air purifiers can be installed in buildings, vehicles, or in the homes of all residents, helping to ensure a clean and fresh air system for everyone. Respiratory diseases will be reduced completely, girls do not need to worry about the risk of dry skin anymore. The city of the future will be smog-free thanks to air purifiers and steam-filled balls ready to cool the city: "The future is a city with no dust, no traffic jams, no beggars, not bad. social distress and no more poor people "An ambulance in this city is also very interesting. These are modern, compact, driverless fast-flying vehicles capable of self-care and rescue of patients in the most challenging terrain. We also do not need to worry about our home when going away in the future. We can shrink our smart home like a backpack and carry it up the mountain or into the sea. Hey, then the hotels will be empty? "The future is when our house can be as small as a backpack and take it with us wherever we go. " Housing is also not a headache for people. Our smart home can have only one room and with the push of a button, we can switch the function and design of a room from the bedroom to the living room or the kitchen. The house also has a self-cleaning and cleaning function, deodorizing, and garbage collection with just one press of a button.