After the Post published a story on Monday disclosing that the government is exploring the feasibility of using Putonghua to teach Chinese language (read News Analysis, October 22), a reader sent us a letter warning the authorities against doing so. He was concerned that future Hong Kong generations would be unable to pronounce Chinese characters in the Cantonese dialect. Only time will tell if his prediction will come true. What is certain is that while Putonghua has been used as the medium of instruction for more than 50 years in mainland China, many local dialects are still widely spoken. In Guangdong, for example, Cantonese is still the street language. In Hong Kong, courses in Shanghainese have emerged to meet the needs of people trying to carve out a career in China's most forward-looking city. Even though everyone in Shanghai also speaks Putonghua, they find it necessary to master the local dialect to be really informed about what is going on around them. This shows that when a dialect is spoken by a substantially large population, it will not be easily forgotten. Back to the issue of whether Putonghua should be used to teach Chinese language at school, my view is that we should, provided that the teachers are competent and students already have a basic grasp of the language. At present, Hong Kong students have only one Putonghua lesson a week. That is not enough to allow them to develop fluency. But my concern about using Putonghua to teach Chinese language is that it could be counter-productive if the teacher does not have a good command of the language. I suspect that many Putonghua teachers have no problem teaching it by following the textbook. But they have trouble using it creatively to talk about a wide range of subjects, which they would have to do if it were to be used to teach Chinese language. My worst fears are that if a teacher with inadequate skills in Putonghua were obliged to use it to teach Chinese language, he or she would revert to a very passive way of teaching and would not be able to stimulate discussion in the classroom. Chinese language classes would then become very boring and students would lose interest in the subject. But if the teacher is a fluent Putonghua speaker and students already have a good foundation in the language, I believe using Putonghua to teach and learn Chinese language will then help to enhance students' Chinese skills. Cantonese is just a dialect spoken in southern China. As Chinese nationals, Hong Kong people simply have to master Putonghua to be able to communicate with fellow Chinese from other parts of the country. CK Lau is Executive Editor, News of the South China Morning Post.