A harmonious society should tolerate the diversity, such as diverse languages, opinions, culture and custom. Take China as an example, we have a diversed society.

I have two reasons on hand.
       First, In a society with various cultures, people can learn the advantage from the different cultures. It's good for the development of society. In China, there are lots of people from the other countries. People from different country have different culture. Also they have various advantage of their culture. For example, German are precise. American are aggresive and brave. Indian are good at math and computor. Chinese are optimistic. People could learn the advantage from the others. The result is that everyone will become better. On the other hand, the French architectures are quite famous for they are artistical and modern. When a French architect comes to China, they will bring the French building style, thought and technology. It's very helpful for the construction of Chinese cities. For example, the new building of CCTV is desgined by a famous French architecture who ever designed the De Gaulle airport. Definitely, our country wll become more beautiful.
      Second, the diversity is a necessary trend for a mature and modern society. In another word, for the thing what we can’t avoid, we have to adapt. Nowadays, in China, there are many migrants in most of big cities. Such as Shanghai, many migrants from southwest and northeast will come to this city, and do their job here. The phenomenon is very helpful for our development of economic. However, as a coin has two sides, it also brings lots of social problems. Government pays much attention and spends much money on solving these kind of problems. Further, In China, different area has different culture, local languege, dressing style, personality, etc. When people from many areas come together. The society becomes very colorful and interesting. When people have a conversation about different culture, they will find many new things which make them surprised and interested.

As a summary, the diversity of a society is necessary. We should enjoy ourselves in it and try to adapt the diversity.

Hello Wang! We can use a pronoun to refer to the noun that has already been mentioned. Please study more on using your punctuations correctly. Combining two sentences together sometimes make them easier to understand and just a little polish of your spelling. Overall, you have an excellent work.