The Art HK fair opened Wednesday with a display of Ai's 2007 "Marble Arm," which depicts an outstretched arm and hand with its middle finger raised.

    The acclaimed artist-activist was taken into custody April 3 during a widespread Chinese crackdown on dissidents, activists, writers and lawyers.

    Last week, China's official Xinhua news agency said Ai faced charges of evading "huge amounts" of taxes and the destruction of accounting documents.

    Human rights activists say China's government often uses accusations of financial wrongdoing as an excuse to arrest dissidents.

    Ai's detention has triggered an international outcry, with art lovers, government officials and human rights advocates across the United States and Europe demanding his release.  His works have been shown globally, including recent exhibitions in New York and London.

    Ai has in recent years has spoken out against the government on several issues.  Among them were shoddy construction practices that resulted in the deaths of many children in schools that collapsed during the Sichuan earthquake in 2008.  Ai also spoke out about the number of Chinese children and infants sickened by contaminated milk powder.

    While Hong Kong is part of China, it enjoys civil liberties not allowed in the rest of the country, including the right to protest and free speech. Activists in the city have protested against Ai's detention.(本文由在线英语听力室整理编辑)