I think it is desirable for secondary school students to wear casual clothes when they are at school.

Firstly, casual clothes make all students feel comfortable. They don't feel constrainted to wear uniform that they don not like.

Secondly, for one thing, casual clothes can also give students freedom of choice. They can choose what sizes, colors, and fashions of clothing they love. And for the other, parents do not worry about their clothes because their children can wear any clothing to school as long as it is clean and tidy.

Finally, casual clothes can make students feel self-confident when they are in their favorite clothes.

In conclusion, in my opinion, all the secondary school students should wear casual clothes.

Study well!

There are a lot of disadvantages of living in a big city, air pollution is among the most serious problems. Firstly, air pollution comes from the factories in the city. Big cities attract a lot of both inside and outside investments, so the number of factories is increasing quickly. This makes the air extremely polluted by smoke from factories. Secondly, that there are too many transportation means also makes this problem worse. Exhaust from cars, motorbike is one of the factors that make the air polluted. To conclude, air pollution, which contributes to making more and more people get many serious diseases, such as lung cancer, tuberculosis and so on, is a big drawback of city life.