Photo taken on Sept. 21, 2009 shows the platform of Yuanmingyuan Park station on Subway Line 4 in Beijng, capital of China. Construction of the 28.2-kilometer-long Subway Line 4 entered the test phase recently. It will start trial operation before China's National Day on Oct. 1st. [Photo:Xinhua]

Workers cleanse glass door at National Library station on Subway Line 4 in Beijng, capital of China, Sept. 21, 2009. Construction of the 28.2-kilometer-long Subway Line 4 entered the test phase recently. It will start trial operation before China's National Day on Oct. 1st. [Photo:Xinhua]

Photo taken on Sept. 21, 2009 shows the platform of Beijing Zoo station on Subway Line 4 in Beijng, capital of China. Construction of the 28.2-kilometer-long Subway Line 4 entered the test phase recently. It will start trial operation before China's National Day on Oct. 1st. [Photo:Xinhua]