中国第一名宇航员称其第一次宇宙飞行时听到神秘的敲击声，但没有人能解释原因。
China's first astronaut says he heard mysterious knocks during his first flight in space - but no one has been able to explain the cause of them.
宇航员杨利伟说，奇怪的噪音让他焦虑，他朝浩瀚宇宙望去，但没看到任何异样。
Astronaut Yang Liwei said the strange noises left him feeling very nervous and he looked out into the vast emptiness of space but couldn't see anything out of the ordinary.
2003年，杨利伟因中国宇宙项目成为中国进入宇宙的第一人，在长达21小时的飞行中，环绕地球数圈。
In 2003 Mr Yang became the first person sent into space by the Chinese space programme, orbiting earth several times during a 21-hour flight.
他在近期访谈中回忆起这次经历，和中国媒体谈起了这莫名其妙啊的敲击声。
He recalled the experience in a recent interview, telling Chinese media the mysterious knocking sounds occurred without rhyme or reason.
杨利伟袒露他听到声音的时候很焦虑，凑近宇宙飞船的门洞调查原因。
Mr Yang revealed he was very nervous when he heard the sounds and moved close to the spaceship's porthole to investigate the cause.
他回地面后，他和宇宙项目的官员解释了噪音，试图用器具模仿声音。
When he returned to earth he explained the noises to officials with the space programme and tried to imitate it with instruments.
杨利伟称这奇怪的噪音从何而来一直都没有说法。他也看不出有什么异样。
Mr Yang says the cause of the strange noises has never been established. He failed to see anything out of the ordinary.