Citizens board a train at a station of the newly-opened subway line in Kunming, capital of Southwest China's Yunnan Province, May 20, 2013. The southern part of the first phase of Kunming subway line 1 and line 2 opened for trial operation on Monday. It's China's first plateau subway. (Xinhua/Lin Yiguang)

A train of the newly-opened subway line attrives at a station in Kunming, capital of Southwest China's Yunnan Province, May 20, 2013. The southern part of the first phase of Kunming subway line 1 and line 2 opened for trial operation on Monday. It's China's first plateau subway. (Xinhua/Lin Yiguang)

A train of the newly-opened subway line arrives at a station in Kunming, capital of Southwest China's Yunnan Province, May 20, 2013. The southern part of the first phase of Kunming subway line 1 and line 2 opened for trial operation on Monday. It's China's first plateau subway. (Xinhua/Lin Yiguang)

Citizens take a train of the newly-opened subway line in Kunming, capital of Southwest China's Yunnan Province, May 20, 2013. The southern part of the first phase of Kunming subway line 1 and line 2 opened for trial operation on Monday. It's China's first plateau subway. (Xinhua/Lin Yiguang)

Citizens take a train of the newly-opened subway line in Kunming, capital of Southwest China's Yunnan Province, May 20, 2013. The southern part of the first phase of Kunming subway line 1 and line 2 opened for trial operation on Monday. It's China's first plateau subway. (Xinhua/Lin Yiguang)