https://www.gov.hk/en/about/abouthk/facts.htm
LanguageChinese and English are the official languages of Hong Kong. English is widely used in the Government and by the legal, professional and business sectors. Trilingual professionals who speak English, Cantonese and Putonghua play a vital role in the numerous enterprises trading in Hong Kong or doing business with mainland China and Taiwan.
https://en.wikipedia.org/wiki/University_of_Hong_Kong
Teaching and learning
Most undergraduate courses are 4-year degrees while the medical and nursing programmes require two and one more year(s) of studies respectively. English is the main medium of instruction, and the University's Senate has endorsed English as the campus lingua franca. Starting from 2012, local students are required to take Academic English courses and Chinese language enhancement courses; however, students who are native-speakers of languages other than Chinese, and students who have not studied Chinese language in their secondary curriculum can be exempted from the Chinese course requirement.[65] Cantonese credit-courses for Mainland Chinese and Taiwan students, and ab initio Mandarin Chinese and Cantonese credit-courses for international and exchange students are offered by the Chinese Language Centre, School of Chinese.