Hongkongers should continue to express their opinions, playwright Sha Yexin said in Hong Kong. The city has experienced many changes and turbulence since the 1997 handover, but Hong Kong remained prosperous and stable under the one-country, two-systems arrangement, he said. Sha said critical democratic voices remain in Hong Kong and that their strength must not ebb. The Shanghai-based writer, who was in the city to promote the upcoming run of his play I am Chairman Mao's Bitch , said he was impressed that so many people continued to join the June 4 candle-light vigil honouring victims of the 1989 Tiananmen Square pro-democracy movement. The July 1 handover anniversary also remains an important protest day, with 150,000 people taking part in the rally this year to express dissatisfaction with social problems and the Hong Kong government. The city supports a robust mix of newspapers, magazines, televisions and radios, of varying political leaning, he said, noting many mainlanders came to Hong Kong to buy political magazines and books about Chinese politics that were banned at home. "In comparison, there is only one voice in the mainland - the voice of the party." Some Hongkongers fear freedom of speech has suffered since the handover. The Hong Kong Journalists Association said in a July report that freedom of speech in Hong Kong had deteriorated over the past seven years. Sha said it was natural Hong Kong people feel protective of the civil liberties guaranteed by the Basic law. "It is best if they can discover problems before they get worse," he said. "The worst case is when Hong Kong people feel nothing when their rights are being impeached." Sha also said he hoped the city can continue to build on its burgeoning cultural sector in the future. There were many amateur drama groups and new shows opening almost every week, more than in Beijing, he said. "I hope more Hong Kong plays can be shown on the mainland and have more interactions with mainland art groups."