(英语作文）Instruction：
Mandarin，or putonghua,is the standard service sector launguage in China. However lately some employees of a metropolis subway company start using dialects to cater to the requirements of people from different areas in order to render better service. Opponents see the countering effects of such movement to the national policy of promoting mandar in across China. Write in 800 words your opinion and support your argument and bring your essay to a natural conclusion in English.