铭记六四天安门，波士顿大图（多图）

This file photo taken on June 3, 1989 shows a dissident student asking soldiers to go back home as crowds flood into central Beijing. (CATHERINE HENRIETTE/AFP/Getty Images) #

In this file photo from May 30, 1989, a student from an art institute plasters the neck of a replica of New York’s Statue of Liberty dubbed the Goddess of Democracy in front of the Great Hall of the People (right) and the monument to the People’s Heroes (center) to promote the pro-democracy protests against the Chinese government at Tiananmen Square in Beijing. (CATHERINE HENRIETTE/AFP/Getty Images) #

This photo taken on May 1, 1989 shows Wang Dan (center), a leading Chinese dissident during 1989 Tiananmen Square pro-democracy demonstrations and member of the Beida students delegaton, addressing foreign correspondents in Beijing. (CATHERINE HENRIETTE/AFP/Getty Images) #

A file photograph from June 3, 1989 shows a dissident student (left) shouting to soldiers, asking them to go back home as crowds flood into central Beijing ahead of the army’s crackdown on pro-democracy protests. (CATHERINE HENRIETTE/AFP/Getty Images) #

Hundreds of thousands of people fill Beijing’s central Tiananmen Square in front of the Monument to People’s Heroes and Mao’s mausoleum in the biggest popular upheaval in China since the Cultural Revolution of the 1960’s in this May 17, 1989 photo. (REUTERS/Ed Nachtrieb) #

An armoured personel carrier crushes one of the tents set up on Tiananmen Square by pro-democracy protestors early Sunday morning in this June 4, 1989 file photo. (REUTERS/Stringer) #

This file photo taken on June 4, 1989 shows an armoured personnel carrier in flames as students set it on fire near Tiananmen Square in Beijing. (TOMMY CHENG/AFP/Getty Images) #

A captured tank driver is helped to safety by students as some in the crowd beat him in this June 4, 1989 photo in Beijing. (REUTERS/Stringer) #

This June 4, 1989 photograph shows a girl, wounded during the clash between the army and students near Tiananmen Square in Beijing being carried out by a cart. (MANUEL CENETA/AFP/Getty Images) #

This file photo taken on June 4, 1989 shows Beijing residents inspecting some of over 20 armoured personnel carriers and other vehicles burnt by demonstrators to prevent the troops from moving into Tiananmen Square in Beijing. (MANUEL CENETA/AFP/Getty Images) #

This photo from June 6, 1989 shows People’s Liberation Army (PLA) tanks and soldiers guarding the strategic Chang’an Avenue leading to Tiananmen Square in Beijing two days after their crackdown on pro-democracy students. (MANUEL CENETA/AFP/Getty Images) #

This file photo taken on June 4, 1989 shows Beijing residents inspecting the interior of one of the armoured personnel carriers burnt by demonstrators to prevent the troops from moving into Tiananmen Square in Beijing. (MANUEL CENETA/AFP/Getty Images) #

In this photo taken on June 5, 1989 and made available for the first time by the AP on Thursday June 4, 2009, three unidentified men flee the scene, as another man (background left) stands alone to block a line of approaching tanks (background right) in Beijing’s Tiananmen Square. This previously unseen photograph was taken by then-AP reporter Terril Jones and came to light after online discussions of the incident on The New York Times’ Lens Blog on the 20th anniversary of the Tiananmen Square crackdown. (AP Photo/Terril Jones) #

A single man blocks an approaching column of PLA tanks on Changan Avenue east of Tiananmen Square in Beijing June 5, 1989 (REUTERS/Arthur Tsang) #

In this June 5, 1989 file photo, a Chinese protestor blocks a line of tanks heading east on Beijing’s Cangan Blvd. June 5, 1989 in front of the Beijing Hotel. The man was shortly pulled away and the tanks continued on their way. (AP Photo/Jeff Widener) #

Fast-forward twenty years to the present, and this is the same view of Changan Avenue, filled with traffic on June 4, 2009. (REUTERS/David Gray) #

Wang Dan (seen as a younger man in photo 4 above), a key figure in the 1989 pro-democracy protests in China, photographed on May 24, 2009, attending a press conference in Taipei. Twenty years on he says he has no regrets over the tumultuous period that transformed him from a college student to a counter-revolutionary. (SAM YEH/AFP/Getty Images) #

On June 2, 2009, three Chinese dissidents, from left to right, Yu Zhijian, Yu Dongyue and Lu Decheng pose beside a photograph of the defaced Chairman Mao portrait, which they had pelted with dye-filled eggs during the 1989 Tiananmen Square democracy movement, in Washington, June 2, 2009. The three men spent much of the past 20 years behind bars for marring the massive portrait at Tiananmen Square, and today say that the students who led that movement have failed to continue the struggle. . (REUTERS/Jim Young) #

Ding Zilin, mother of 17-year-old pro-democracy demonstrator Jiang Jielian who was killed during the 1989 army crackdown on Tiananmen protesters, weeps as she talks about the event in her Beijing flat during an interview on April 7, 2009. Twenty years on, Ding’s pain is still as raw as it was when her son was shot through the heart in the army crackdown on Tiananmen Square protesters in China, an event that she says broke her. (PETER PARKS/AFP/Getty Images) #

A Chinese paramilitary police officer stands guard near Tiananmen Square in Beijing, China, on Thursday, June 4, 2009. China opened Tiananmen Square to the public this morning after ringing the area with metal fences overnight to stop people from commemorating the 20th anniversary of the army’s 1989 crackdown on pro-democracy demonstrators. (Nelson Ching/Bloomberg News) #

A plain-clothes policeman attempts to use an umbrella to block the view of soldiers patrolling the area adjacent to Tiananmen square from the media in Beijing, China, Wednesday, June 3, 2009. Foreign journalists were barred from Beijing’s Tiananmen Square on Wednesday amid heavy security on the eve of the 20th anniversary of the bloody crackdown on 1989 pro-democracy protests. (AP Photo/Elizabeth Dalziel) #

A giant statue of former Communist Party chairman Mao Zedong is seen behind a red wall at the campus of Fudan University in Shanghai June 4, 2009. (REUTERS/Nir Elias) #

Chinese paramilitary policemen in silhouette watch over one of the entrances to Tiananmen Square on June 3, 2009. Chinese police had tightened restrictions on perceived trouble makers on the eve of the 20th anniversary of the crackdown on Tiananmen democracy protests. (PETER PARKS/AFP/Getty Images) #

Paramilitary policemen, some dressed in plain-clothes and others in uniform, march in formation past members of the public after the flag raising ceremony in front of the giant portrait of Chairman Mao Zedong on Beijing’s Tiananmen Square June 4, 2009. (REUTERS/David Gray) #

Customers use computers at an internet cafe in Changzhi, Shanxi province June 3, 2009. Access to many popular websites was suddenly blocked by the Chinese government two days before the 20th anniversary of the crackdown, including YouTube, Blogspot, Tumblr, Livejournal, Flickr, Twitter and Bing. (REUTERS/Stringer) #

Chinese police check documents of foreign journalists trying to enter Tiananmen Square on June 4, 2009. Foreign media were harrassed and barred as China kept Tiananmen Square under tight surveillance for the anniversary. (PETER PARKS/AFP/Getty Images) #

A plane flies past “Pillar of Shame — A memorial for Tiananmen” by Danish artist Jens Galschiot which is being displayed at the University of Hong Kong May 26, 2009, on the tenth day count-down to the 20th anniversary of the June 4th military crackdown on pro-democracy protesters in Beijing’s Tiananmen Square in 1989. (REUTERS/Bobby Yip) #

Tens of thousands of people attend a candlelight vigil at Hong Kong’s Victoria park Thursday, June 4, 2009, to mark the 20th anniversary of the June 4th military crackdown on the pro-democracy movement in Beijing. (AP Photo/Vincent Yu) #

A young girl grabs the candle from her father to join the crowd at Victoria Park, Hong Kong on June 4th, 2009. The next generation remembering it even after 20 years. (© Y. C. William Wang) #

A man holds a candle as tens of thousands of people attend a candlelight vigil at Hong Kong’s Victoria park Thursday, June 4, 2009. (AP Photo/Vincent Yu) #

A statue of the Goddess of Democracy is displayed at Hong Kong’s Victoria Park Thursday, June 4, 2009, ahead of a planned candlelight vigil later in the evening to mark 20th anniversary of the June 4 military crackdown on the pro-democracy movement in Beijing. (AP Photo/Vincent Yu) #