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. (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. (Xinhua)

Workers work at National Library 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.(Xinhua)

Photo taken on Sept. 21, 2009 shows the wall with animal images at 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. (Xinhua)

Photo taken on Sept. 21, 2009 shows the external of the entry 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. (Xinhua)

Workers try the ticket check-in sysytem 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. (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. (Xinhua)